Fixed naming of Opauth.

README.md

 
 * [Sentry](https://github.com/cartalyst/sentry) - A framework agnostic authentication & authorisation library.
 * [Sentry Social](http://docs.cartalyst.com/sentry-social-2/introduction) - A library for social network authentication.
-* [OPAuth](https://github.com/opauth/opauth) - A multi-provider authentication framework.
+* [Opauth](https://github.com/opauth/opauth) - A multi-provider authentication framework.
 * [OAuth2](https://github.com/php-loep/oauth2-server) - An OAuth2 authentication server, resource server and client library.
 * [OAuth2 Server](http://bshaffer.github.io/oauth2-server-php-docs/) - Another OAuth2 server implementation.
 * [PHP oAuthLib](https://github.com/Lusitanian/PHPoAuthLib) - Another OAuth library.