Update A0TwitterAuthenticator.m

BDBOAuth1Manager (https://github.com/bdbergeron/BDBOAuth1Manager/commit/2a6d37a8abc7f512daaff2e220dae1f4245ae1cc) renamed the "BDBOAuthToken" to "BDBOAuth1Credential".
This update fixes this change.
Merge pull request #53 from RealBrubru/patch-1

Update A0TwitterAuthenticator.m