Adding a UIView contentView to the alert for generic usage

- Adding a generic UIView on the alert to supply the feature removed from early versions iOS 7 betas. (can be used as UIImageViews, TableViews, or any other UIView subclass)
- Added the parallax effect commited by @Fr4ncis with some little tweeks
- Removal of some warnings due API's deprecation
- Code is iOS 7 only

Usage: Just set the property -contentView: or alloc/init with the designated initializer and you're good to go.

Usage example:

![img_6248](https://f.cloud.github.com/assets/2243183/1070280/2e6aabfa-144a-11e3-8eb2-6eecc966fc86.PNG)