[shell] use prod mode in generated start script
[shell] introduce settings loading in generated app

 and move some string properties to this file
[shell] add unsecured resource in generated hello resource

Makes it easier to test the REST API
[minor] remove unchecked warning
[all] make code compile with java8 compiler

mostly javadoc fixes + don't use import java.util.* when importing Guava Optional too.
[minor] fix factory test, failing on java 8