A Servlet com url = /contato não está sendo encontrada.
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
</dependency> <plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.3.7.v20160115</version>
<configuration>
<scanIntervalSeconds>10</scanIntervalSeconds>
<webApp>
<contextPath>/test</contextPath>
</webApp>
</configuration>
</plugin>