Possible fix for the test_model_validation_failure

...test failure when running tests with Django 1.7b4.
Merge branch 'v0.5.X' into possible-fix-fieldscribbleform-has-no-field-whatever
Merge pull request #82 from caktus/possible-fix-fieldscribbleform-has-no-field-whatever

Possible fix fieldscribbleform has no field whatever