Cherry pick of bcylin/CSNotificationView 23c277e434e3b70e51eb3d427562cd0b8f5ef88c. Changed deployment target to 6.0 and added conditional code for setting bar background aka tint color.
Adjusted _textLabel configuration to make multiline-label work on iOS 6 although auomatic font-size-shrinking is not available there. See comments in iOS 7 / 6 specific code.
Update podspec to be compatible with iOS 6