check term permissions to ensure that the add new term ui only shows up for those with those permissions

I am using 2.0.0-rc12 and I still get the Add term even though the Anonymous user is making the selection. Do I have to pin the rc-4 to get the old behavior back?

I've attached a patch that will suppress the "new term" input when the widget is not configured to allow for the creation of new terms

Patch #6 working perfectly, thanks :)