Use this function to extend this repository with the appropriate collectionName and perhaps other stuff.
@param  {Object} obj The object that should be extended.
@return {Object}     The extended object.
function (obj) {
    var res = _.assign(_.assign({}, this), obj);
    for (var f in this) {
      if (_.isFunction(this[f])) {
        res[f] = this[f];
      }
    }
    if (_.isFunction(res.checkConnection)) {
      res.checkConnection();
    }
    return res;
  }