Test to expose a regression in handling enhanced types.

The enhanced_types annotation is somehow not being propagated
to the generated code. This breaks TBSONProtocol and TReadableJSONProtocol.

A future change will include a fix. For now it's better to have a broken test
in master than code that seems like it works but doesn't.
Merge pull request #23 from foursquare/enhanced_type_test

Test to expose a regression in handling enhanced types.