Update README.md
Update README.md
Update PKRevealController.podspec
Update PKRevealController/Controller/UIViewController+PKRevealController.m

As mentioned in issue #78 having a retained association would cause a retain cycle. Weakly linking the controllers in the PKRevealController.h ain't good style, thus assign the association.
Fixing issue #80. - Some refactoring and better logic.
Merge branch 'development'