Update project file deployment target to iOS 7 for 64-bit builds.
Update project file deployment target to iOS 7 for 64-bit builds.

Reviewed By: chrisp

Test Plan: Built via XCode 5.

hibu/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,hibu/facebook-ios-sdk,shepting/facebook-ios-sdk,shepting/facebook-ios-sdk,Subsplash/facebook-ios-sdk,flovilmart/facebook-ios-sdk,Subsplash/facebook-ios-sdk,wooga/facebook-ios-sdk,flovilmart/facebook-ios-sdk,tipbit/facebook-ios-sdk,beamly/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,tipbit/facebook-ios-sdk,1234-/facebook-ios-sdk,beamly/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,shepting/facebook-ios-sdk,tipbit/facebook-ios-sdk,shepting/facebook-ios-sdk,taptaptap/facebook-ios-sdk,flovilmart/facebook-ios-sdk,flovilmart/facebook-ios-sdk,FiftyThree/facebook-ios-sdk,1234-/facebook-ios-sdk,FiftyThree/facebook-ios-sdk,shepting/facebook-ios-sdk,wooga/facebook-ios-sdk,1234-/facebook-ios-sdk,1234-/facebook-ios-sdk,Subsplash/facebook-ios-sdk,wooga/facebook-ios-sdk,flovilmart/facebook-ios-sdk,FiftyThree/facebook-ios-sdk,hibu/facebook-ios-sdk,taptaptap/facebook-ios-sdk,hibu/facebook-ios-sdk,1234-/facebook-ios-sdk,hibu/facebook-ios-sdk,taptaptap/facebook-ios-sdk,ArtLapitski/facebook-ios-sdk,beamly/facebook-ios-sdk