Add /v3/releases/:module endpoint. Bug fixes. Add some unit tests.

1. Fix json content type
2. Add v3 releases end-point
3. Fix bug in logger constructor
4. Fix Gem to puppet version conversion
5. Replace / to - in module names for v3 proxy backend
6. Fix loggoing in v3 modules api
7. Add a few UTs
8. Add Rakefile
9. Update travis to run test:all task
10. Bump version