Issue70/addgsonsupport

Items in this pull request:
- [x]  Squashed 76760da, 7063638 and 294f1dd into a single commit (also added d1fe751)
- [x]  Reference issue 70 in the commit message
- [x]  Removed 38209f3 from the PR (and adjusted AnnotationStyleIT so it will work without it)
- [x]  Added roundtrip JSON integration test covering Gson annotated types
- [x]  Added GenerationTestSupport to, hopefully make adding "roundtrip" easier
- [x]  Added GsonIT as an example of this
- [x]  Added several sample files for integration test input
- [ ] Adjust tabs/spaces scheme to match the project [1]
- [ ] Additional I.T. for other annotation types [2]

[1] I have not yet adjusted tabs/spaces because I'm not sure if that's an issue. For now, I just used Eclipse's default settings which uses ***mixed*** spacing. However, this isn't showing properly on github and may need to be converted to ***spaces only***.

[2] Additional "roundtrip" integration tests can easily be added for other annotation types but I didn't include that as part of this Gson P.R.