Fixed behavior when combined area and Remote attribute

By adding a AreaReference enum, to be capable of setting Remote attribute or use the area which.
So, fix the problem of not being able to refer to the controller outside the area from inside the area.
Address CR comments on previous commit
- add XML comments
- use named parameters in added test methods (clarify nulls)
- rename added test methods to make expectations clear
- add three new tests to cover gaps