Improve performance of adding commands to PFCommandCache.
Improve performance of adding commands to PFCommandCache.

ParsePlatform/Parse-SDK-iOS-OSX,podkovyrin/Parse-SDK-iOS-OSX,ParsePlatform/Parse-SDK-iOS-OSX,gonzalonunez/Parse-SDK-iOS-OSX,podkovyrin/Parse-SDK-iOS-OSX,gonzalonunez/Parse-SDK-iOS-OSX