Auto process pending permission requests upon verification (accept verified users only)

[ammar257ammar]

This fix will adds a signal to the Verification model which will check all pending requests and accept them if the user is verified and the object (which the permission is requested for) has a request handling setting of accepting verified users only. Also, for the same objects, pending requests of unverified users will be rejected. An explanation is added to the rejection message if the user is not verified.

closes #2461