Update unf dependency to ~> 0.1.0
Merge pull request #89 from sferik/update_unf_dependency

Update unf dependency to ~> 0.1.0
Remove Hash extension.
Implement symbolize_keys and symbolize_keys! as a helper (HashHelper),
avoiding conflicts with projects stuck with old activerecord (~> 2.3.18)
and/or old Rails (2).
Merge pull request #90 from dadah89/igor/symbolize_keys

Move Hash symbolize_keys/symbolize_keys! to a helper module.