Added persistence on high score and square count. Not able to test sound.
Fixed First Session Bug
Pre Merge Commit - Fixed minor issues
Merge branch 'master' into UserDefaults
Merge pull request #16 from ranleung/UserDefaults

User defaults
Added GameCenter Button and Image
Merge pull request #17 from ranleung/GameCenterButton

Added GameCenter Button and Image
Merge branch 'master' into helpScreenLayout
Small merge conflict fixed