Update UIViewController+CWPopup.m

[angelolloqui]

Added controllers as child controllers instead of manually call appear methods

[angelolloqui]

With the previous implementation my child controllers of the presented one were not receiving appearance methods. Also, the willAppear was invoked before the view gets its major settings such as shadows or corner radius, not allowing to change them if needed.

With the new ones the appear/disappear methods work as expected and are also valid for child controllers.