added reddit provider

Just made a Reddit provider.

Though Reddit, uses the "bearer" oauth2 method, so a bit work needed to be done.

Would it be a good idea to implement [PHP-OAuth2](https://github.com/adoy/PHP-OAuth2) for OAuth2 requests? PHP-OAuth2 can handle all 4 types URI, BEARER, OAuth and MAC.

Another thing, I got pretty tired of writing all the ***_id and ***_access_token in my entity, so I wrote traits for my entity - Would you want me to implement these in the bundle?