show global scores from OpenKit
updated GC Login methods to not create OKUser
removed gamecenter_id from OKUser and all corresponding references
update getSocialScores to not pull scores from GameCenter
add NSCoding to OKScore
created OKScoreCache singleton class to store scores in NSUserDefaults
stop submitting twice on scoresubmitted
move sorting from view to leaderboard model
show local cached top score in leaderboards
submit cached scores on user login, clear cached scores on user logout
check for cached scores on OKManager initialization
Merge branch 'UpdateGCWrapper' into development