Update CustomIOS7AlertView.m

- Solved some screen rotation issues.
- Users can Enable/Disable certain screen orientation by 
orientationPortraitEnabled, orientationPortraitUpsideDownEnabled, orientationLandscapeLeftEnabled, orientationLandscapeRightEnabled
- Fixed some pixel hinting issues on retina
- Buttons added now are arranged vertically like the native iOS7 UIAlertView
- To enable/disable buttons added, use the buttonStatuses property.