Use upstream instead of an untested downstream

README.md

 * [PHP oAuthLib](https://github.com/Lusitanian/PHPoAuthLib) - Another OAuth library.
 * [Sentinel Social](https://cartalyst.com/manual/sentinel-social/2.0) - A library for social network authentication.
 * [Sentinel](https://cartalyst.com/manual/sentinel/2.0) - A framework agnostic authentication & authorisation library.
-* [TwitterOAuth](https://github.com/ruudk/twitteroauth) - A Twitter OAuth library.
+* [TwitterOAuth](https://github.com/abraham/twitteroauth) - A Twitter OAuth library.
 * [TwitterSDK](https://github.com/lyrixx/twitter-sdk) - A fully tested Twitter SDK.
 
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