isStarred(cb) {
      return this._request204or404(`/user/starred/${this.__fullname}`, null, cb);
   }
Check if a repository is starred by you
@see https://developer.github.com/v3/activity/starring/#check-if-you-are-starring-a-repository
@param {Requestable.callback} cb - will receive true if the repository is starred and false if the repository
                                 is not starred
@return {Promise} - the promise for the http request {Boolean} [description]