Various fixes and additions

Added userInfo property kOmniAuthTwitterUserInfoKeyOverrideExistingAccount to allow overriding existing account on saveAccount if account exists already.
Updated AFOAuth1Client to ~> 0.3.0
Fixed issue using NSJSONSerialization when data parameter could be nil.
Fixed more potential issues with creating a NSDictionary with nil values
Fixed potential issue when response may not contain oauth_token or oauth_token_secret.
Fixed error handler to return not successful for completionBlock on performReverseAuthForAccount
Updated non-granted response to expected dictionary type
Fixed performLoginForNewAccount to only attempt saving credentials if access was granted otherwise continue on for oauth non-native based auth
For access not granted and no account, attempt to create one or login otherwise with performLoginForNewAccount
Added support for access not granted error for ACAccountStore requestAccessToAccountsWithType