Changed typedef enum to use NS_ENUM macro to be swift compatible

With XCode-Beta4, we can no longer compare Facebook enums with .value, this change updates all the typedef enum to use the NS_ENUM macro, so they will be SWIFT compatible.

https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/InteractingWithCAPIs.html

This also includes pgaspar's changes to rename FBGraphObject protocol to FBGraphObjectProtocol