temporary_invitation 5.x-2.0

Ok people, it's time to release the final 2.0.

* One more last-minute feature: An option "Don't assign roles to existing users" which comes in handy if you want to assign a "Temporary User" role to newly created temporary users but not to merely invited ones.
* Doing the code style maniac: Get rid of a NULL parameter which is now assumed by default.

That's it folks. Have fun, and hope for point releases instead of new release candidates :)