constructor(fullname, auth, apiBase) {
      super(auth, apiBase);
      this.__fullname = fullname;
      this.__currentTree = {
         branch: null,
         sha: null,
      };
   }
Create a Repository.
@param {string} fullname - the full name of the repository
@param {Requestable.auth} [auth] - information required to authenticate to Github
@param {string} [apiBase=https://api.github.com] - the base Github API URL