Prevent class attributes name clashes.

[budu]

Here's my fix for #156

[airblade]

Thanks for this.

Unless I'm mistaken, the :if and :unless options have got lost in the refactoring. Please could you add them back in?

[budu]

I'm not sure if there's something wrong with the :if and :unless options, the test 'A record with defined "if" and "unless" attributes' pass on my machine, do you have an example which doesn't work?

[edtsech]

@budu, Do you have this error in test suite test_versions_works_with_custom_timestamp_field?

[budu]

Not on my side, all test pass.

[edtsech]

My bad, all test pass. Btw good pull request.