Feature/representor factory

@mszenher Please review and merge after merging PR https://github.com/mdsol/crichton/pull/17

This PR implements a factory for generating adapters for dynamically wrapping hashes, but also objects to act as Representors.

All specs passing:

Finished in 4.08 seconds
257 examples, 0 failures, 1 pending
Coverage report generated (99.93%) covered.