Added base template for config ui.

appengine/config_service/ui/bower_components/polymer/polymer-element.html

+<!--
+@license
+Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<link rel="import" href="lib/mixins/element-mixin.html">
+<script>
+(function() {
+  'use strict';
+
+  /**
+   * Base class that provides the core API for Polymer's meta-programming
+   * features including template stamping, data-binding, attribute deserialization,
+   * and property change observation.
+   *
+   * @polymerElement
+   * @memberof Polymer
+   * @constructor
+   * @implements {Polymer_ElementMixin}
+   * @extends HTMLElement
+   * @mixes Polymer.ElementMixin
+   * @summary Custom element base class that provides the core API for Polymer's
+   *   key meta-programming features including template stamping, data-binding,
+   *   attribute deserialization, and property change observation
+   */
+  const Element = Polymer.ElementMixin(HTMLElement);
+  Polymer.Element = Element;
+})();
+</script>