Authenticate to Renren utilizing OAuth 2.0 and retrieve basic user information.
@example Basic Usage use OmniAuth::Strategies::TaoBao, ‘client_id’, ‘client_secret‘
@param [Rack Application] app standard middleware application parameter @param [String] client_id the app key at taobao open platform @param [String] client_secret the app secret at taobao open platform @option options [String]
[Validate]