LoadPackage = function (id, resources) {
  this._id = id;
  this._promise = null;

  // assemble resources
  this._resources = PKGS.getPkgForIdentifier(id);
  if (resources != null && resources.length > 0) {
    this._resources = this._resources.concat(resources);
  }
}
Load package object.
@param {String|Number|Integer} id
@param {Array} resources
@constructor