Use properties instead of ivars for internal variables
Update contributors in readme
Fix an issue where the first tap can be interpreted incorrectly

See these tweets for details:
https://twitter.com/Padraig/status/332628116121980928
https://twitter.com/Padraig/status/332630523388239872
Update readme with CocoaPods install instructions
Update project settings to new defaults (Xcode 4.6)
Enable very strict compiler warnings in demo project

-Wall -Wextra
Turn on Automatic Reference Counting (ARC)

This also fixes two memory leaks in OBShapedButton.m (_buttonImage and _buttonBackground were not released in dealloc).
Update code formatting and coding style
Add CocoaPods podspec for v1.0.2