Merge pull request #7 from rivera-ernesto/cornerRadius

Corner radius property
Merge pull request #6 from rivera-ernesto/ios5_support

iOS 5 support
Rename buttonColor -> originalBackgroundColor
Simplify abridged init method
No need to validate radius as it is always a valid CGFloat value
Do not override Interface Builder font
Override setBackGroundColor instead of using makeFlat:withBackgroundColor:

Enables changing the background color after initialization
Move action setting out of setter
Add missing control events to actions
Merge pull request #8 from rivera-ernesto/refactor

Refactor
Update README.md
bump version. update minimum version
fixed versions
updated example to show a button from code
Re-enable iOS 5/6 support
Make example app iOS 5/6 compatible
Merge remote-tracking branch 'fork/ios_5_6_compatibility'