code: function readfile(fullpath, options, cb) {
      if (2 === arguments.length) { cb = options; }
      get(self.endpoint + '/contents' + fullpath + self.refparam, function(err, json) {
        if (err) return cb(err);
        cb(null, Buffer.from(json.content, 'base64'));
      });
    }
docs: matches fs.readfile()