DTAlertView: Moved action block to delegate clickedButtonAtIndex: method
DTProgressHUDDemo: Added DTAlertView example
DTAlertView: Remove duplicated init method

Only one designated initializer should exist per class.
DTActionSheet: Fixed to work on iOS 8
DTAlertView: Improved initalizers design so all three initializers work correctly
DTProgressHUD: Updated DTActionSheet and DTAlertView examples
DTAlertView & DTActionSheet: Improved unit tests to cover all three possible initalizers
Project: Added DTActionSheet unit test
DTActionSheet & DTAlertView: Changed designated initializer back to init so all initializers work correctly on iOS 8, iOS 7 and iOS 6.

Also updated examples a little.
Merge pull request #73 from obviousengineering/dtactionsheet

DTActionSheet & DTAlertView working on iOS 6, 7 & 8