Merge pull request #1 from tomkersten/master

The "inheritable_attributes" module was renamed to "attribute" at some point since the gem was released. Everything appears to work correctly by changing that require statement.
Update rspec requirement
Prepare for release 0.2.13
Remove code generating deprecation warnings

* 'write_attribute' deprecation warnings being generated
  in #cache_person_name. This is not a clean fix, but it removes
  the warnings...