iOS plugin installation action implementations

Implements the plugin installation actions for iOS. Adds a new library
for making changes on the .pbxproject files. makes some changes to the
general installation actions framework to accomodate values needed on
iOS. Refreshes the plist library to pick up a show stopper bug fix. And
adds a series of tests.
Move to Cordova version 3.1

Moves the cordova runtime used to version 3.1. Adjusts the
XcodeProjectGenerator to compensate for layout & filename changes. Also
fixes a bug with launch configuration.