Bumped Ruby to 2.1.2, cleanup

[Task 378] (https://integracredit.acunote.com/projects/44826/tasks/378) - EnumStateMachine: bump ruby to 2.1.2

### Changes
* Updated Ruby to 2.1.2, ActiveModel and ActiveRecord to 4.0.5
* Code cleanup

### Tests
```
Finished tests in 6.773683s, 270.3108 tests/s, 336.8921 assertions/s.
1831 tests, 2282 assertions, 0 failures, 0 errors, 0 skips
```