Allow setting default value on field_domain_access

I have a situation where I'd like some users to be allowed to publish content on a second domain, but have everyone go trough the "main" domain to create content.

Is it something that this patch would help to cover ?

Here's interdiff for 24 to 33, it does look like 24 incorrectly referred to a constant that wasn't defined.

This patch no longer applies

Attached is an updated patch for 2.0.0-beta2

can confirm that @johnjw59 's patch works on 2.0.0-beta2 and the Oct dev version.
It would be ideal to have an option to choose which domain to be the default, though.