Bumps rspec to 3.0.0.beta2 and fixes deprecation warnings

We are using cancan in a rails 4 project. When we upgraded to rspec 3.0.0.beta2 we got a few deprecation warnings from cancan. Upon investigation, cancan seems to be dead but we found that cancancan seemed to be the successor.

To fix the deprecation we bumped rspec to 3.0.0.beta2 and fixed all the deprecation warnings. All the specs pass and I'm currently using this branch in our rails 4 project (everything still green).

I'm not sure what the plan is for cancancan and rspec compatibility, but if you want to move to rspec 3, this is a good starting point for you.

Enjoy.
You also could update to `'~> 3.0.0'`