Fix issue where apps with their Facebook URL scheme at indexes other than 0 in their Info.plist would not launch Facebook.app for auth.

Iterates through each of the available URL types and flattens the schemes in each into one dictionary when checking in the -isRegisteredURLScheme: method. This change resolves this issue http://stackoverflow.com/questions/16113688/failing-to-open-active-session-after-updating-facebook-sdk-to-3-5