Eu tentei instalar o Ionic através do comando "npm install -g ionic@1" que está no exercício, porém eu sempre recebo a seguinte mensagem:
C:\Users\allan\AppData\Roaming\npm\ionic -> C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\bin\ionic
> node-sass@3.8.0 install C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass
> node scripts/install.js
Cannot download "https://github.com/sass/node-sass/releases/download/v3.8.0/win32-x64-57_binding.node":
HTTP error 404 Not Found
Hint: If github.com is not accessible in your location
      try setting a proxy via HTTP_PROXY, e.g.
      export HTTP_PROXY=http://example.com:1234
or configure npm proxy via
      npm config set proxy http://example.com:8080
> node-sass@3.8.0 postinstall C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass
> node scripts/build.js
Building: C:\Program Files\nodejs\node.exe C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\bin\node-gyp.js rebuild --verbose --libsass_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=
gyp info it worked if it ends with ok
gyp verb cli [ 'C:\\Program Files\\nodejs\\node.exe',
gyp verb cli   'C:\\Users\\allan\\AppData\\Roaming\\npm\\node_modules\\ionic\\node_modules\\ionic-app-lib\\node_modules\\node-sass\\node_modules\\node-gyp\\bin\\node-gyp.js',
gyp verb cli   'rebuild',
gyp verb cli   '--verbose',
gyp verb cli   '--libsass_ext=',
gyp verb cli   '--libsass_cflags=',
gyp verb cli   '--libsass_ldflags=',
gyp verb cli   '--libsass_library=' ]
gyp info using node-gyp@3.3.1
gyp info using node@8.0.0 | win32 | x64
gyp verb command rebuild []
gyp verb command clean []
gyp verb clean removing "build" directory
gyp verb command configure []
gyp verb check python checking for Python executable "python2" in the PATH
gyp verb `which` failed Error: not found: python2
gyp verb `which` failed     at getNotFoundError (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:14:12)
gyp verb `which` failed     at F (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:69:19)
gyp verb `which` failed     at E (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:81:29)
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:90:16
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\index.js:44:5
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\windows.js:29:5
gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21)
gyp verb `which` failed  python2 { Error: not found: python2
gyp verb `which` failed     at getNotFoundError (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:14:12)
gyp verb `which` failed     at F (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:69:19)
gyp verb `which` failed     at E (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:81:29)
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:90:16
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\index.js:44:5
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\windows.js:29:5
gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21) code: 'ENOENT' }
gyp verb check python checking for Python executable "python" in the PATH
gyp verb `which` failed Error: not found: python
gyp verb `which` failed     at getNotFoundError (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:14:12)
gyp verb `which` failed     at F (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:69:19)
gyp verb `which` failed     at E (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:81:29)
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:90:16
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\index.js:44:5
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\windows.js:29:5
gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21)
gyp verb `which` failed  python { Error: not found: python
gyp verb `which` failed     at getNotFoundError (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:14:12)
gyp verb `which` failed     at F (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:69:19)
gyp verb `which` failed     at E (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:81:29)
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\which.js:90:16
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\index.js:44:5
gyp verb `which` failed     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\node_modules\which\node_modules\isexe\windows.js:29:5
gyp verb `which` failed     at FSReqWrap.oncomplete (fs.js:152:21) code: 'ENOENT' }
gyp verb could not find "python". guessing location
gyp verb ensuring that file exists: C:\Python27\python.exe
gyp ERR! configure error
gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.
gyp ERR! stack     at failNoPython (C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\lib\configure.js:401:14)
gyp ERR! stack     at C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass\node_modules\node-gyp\lib\configure.js:356:11
gyp ERR! stack     at FSReqWrap.oncomplete (fs.js:152:21)
gyp ERR! System Windows_NT 10.0.15063
gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Users\\allan\\AppData\\Roaming\\npm\\node_modules\\ionic\\node_modules\\ionic-app-lib\\node_modules\\node-sass\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--libsass_library="
gyp ERR! cwd C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\node_modules\ionic-app-lib\node_modules\node-sass
gyp ERR! node -v v8.0.0
gyp ERR! node-gyp -v v3.3.1
gyp ERR! not ok
Build failed
npm ERR! Cannot read property 'type' of undefined
npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\allan\AppData\Roaming\npm-cache\_logs\2017-06-09T20_33_14_545Z-debug.log
E quando eu executo o "ionic resources", aparece a seguinte mensagem:
module.js:487
    throw err;
    ^
Error: Cannot find module 'C:\Users\allan\AppData\Roaming\npm\node_modules\ionic\bin\ionic'
    at Function.Module._resolveFilename (module.js:485:15)
    at Function.Module._load (module.js:437:25)
    at Function.Module.runMain (module.js:605:10)
    at startup (bootstrap_node.js:158:16)
    at bootstrap_node.js:575:3
Alguém sabe alguma maneira de resolver este problema?