Fix locale not supporting underscores

[Tarpsvo]

Fix #26

[freekmurze]

Have you tested these changes?

[Tarpsvo]

Hey!

Yes I have. I tested it manually with models that had up to 6 different locales and it worked as expected.

I do not know why the field was previously decoupled from the original attributes though (resorted to parsing the modified attribute string, instead of using the original attributes), even though all the original data was available ($locale, $originalAttribute).

[freekmurze]

Thanks!