Part 3: Generators layout and generate stub rest resources

Not related to this PR:

I know google collections are very useful and we all hate RPC but using these collections adds I'm guessing about 80KB to any GWTP rpc project that serializes maps and lists.  This can be resolved by the user manually blacklisting them, but most people won't do that.  Anyway if we get rid of Guava as a dependency for GWTP a lot of users will see an improvement in compile size.