changed that self.delegate is not overridden because UIAlertView seems to use self.delegate internaly in iOS8.
This caused that the block callbacks did not work anymore.
So I introduced a property alertViewDelegate, that can be uses like the UIAlertView delegate property.
If someone uses the setDelegate methods, a warning is shown.
Fixed iOS8 problems in DTActionSheet, created demo for DTActionSheet
Fixed DTAlertView test on iOS7, now I don't call a show -> (was iOS problem)
Preventing warning when delegate is set nil
didPresentActionSheet: and willPresentActionsheet: now check for the appropriate selector on the actionSheetDelegate
Merge pull request #78 from MPiccinato/DelegateForwardingFix

Crash on didPresentActionSheet: and willPresentActionsheet:
DTActionSheet: Use UIActionSheetDelegate protocol rather than UIAlertViewDelegate one
DTAlertView: Removed no longer needed _externalDelegate ivar
Removed unnecessary files from action sheet demo causing warnings
Merge branch 'obviousengineering-actionsheet-alertview' into develop