Changed plugin methods for Cordova 1.9 compatibility.
Fixed data argument not used by format string warnings.
Changed plugin callback system and authentication.

- Removed automatic authentication.  Now users of the plugin must explicitly
  call authenticate providing success and failure callbacks.

- Changed callback system so that users of the plugin can explicitly provide
  callbacks to be invoked for authenticate, reportScore, and getAchievement.

- Added onshow and onhide properties that client code can use to register
  functions gamecenter show/hide callbacks.
Renamed method getAchievement to reportAchievement.
Fixed bug with setting leaderboard category.
Merge pull request #1 from wcwynn/v1.9

Implemented Cordova 1.9 compatibility.
Updated the plugin to Cordova 2.3.
Merge pull request #2 from wcwynn/v2.3

Updated the plugin to Cordova 2.3.
Updated README.md.

- Added a note to indicate that the GameKit.framework is required.
- Updated configuration instructions from referencing Cordova.plist to
  config.xml.
Merge pull request #4 from wcwynn/v2.3

Updated README.md.
Added example app.
Updated the README.md.

- Added a README for the example app.
Merge pull request #6 from wcwynn/v2.3

Added an example app and updated the README.
Fixed memory leak when leaderboard/achievements opened multiple times.
Restructured the example.
Merge pull request #10 from wcwynn/v2.3

Fixed memory leak when leaderboard/achievements opened multiple times.
Updated the plugin and example to Cordova 2.4.
Updated the plugin and example to Cordova 2.5.
Updated the plugin and example to Cordova 2.6.
Updated the plugin and example to Cordova 2.7.