Refactor Ability#can? method

[ryanb]

The can? method is currently one of the most complex methods in CanCan. It could use some refactoring! Splitting it up into some private methods would probably be best.

Alternatively I could create a separate AbilityCheck object which would reduce the amount of parameter passing across methods, but I'm concerned about performance since the can? method is triggered frequently in many applications.

I wonder if I can move some of the checking logic to up-front inside the can call. I'll have to look into that as well.

[ryanb]

refactoring ability can? method - closed by c40490d