Set auto_initialize to false for province field

This fixes a bug I was having with my unit tests when submitting a form using Symfony's 'WebTestCase' class.

I'm using Symfony 2.3 and I only see this bug in my tests, when running the app in dev mode I don't get any error, but the error I do see is described in 2.3's upgrade docs

https://github.com/symfony/symfony/blob/master/UPGRADE-2.3.md

Search for the section that contains "Automatic initialization is only supported on root forms."

I've only submitted a patch for my specific case, but I can imagine it won't be the only place that needs fixing.