Bug when adding/modifying an integer field with value 0.

[Jurriaan Bremer]

There's a bug where if I'm adding or modifying an integer field with the value 0, that it flashes a "No value entered" message (or something along these lines.)
I quickly looked at the problem a few weeks ago, and it's related to using the incorrect validator or so, which results in a "if not value:" statement, which naturally should be more along the lines of "if value is None:".

Thanks for the plugin :)