update elements and fix some bugs

lib/src/google-streetview-pano/google-streetview-pano.html

 <link rel="import" href="../polymer/polymer.html">
 <link rel="import" href="../google-apis/google-maps-api.html">
 
 <!--
 Element for generating a Google Maps Street View Panorama.
 
 ##### Example
 
     <google-streetview-pano
       pano-id="CWskcsTEZBNXaD8gG-zATA"
       heading="330"
       pitch="-2"
       zoom="0.8"
       disable-default-ui>
     </google-streetview-pano>
 
 There are tons of great panoramas on the [Google Maps | Views page](https://www.google.com/maps/views/home?gl=us)
 
 To grab a panorama, look at its url in the address bar. For example:
 
 google.com/maps/views/view/102684927602131521305/photo/**1szTnskrdKIAAAGuu3fZRw**
 
 The hash in bold is the `pano-id`. You'll often need to dial in the `heading`, `pitch` and `zoom` manually.
 
+You can also use the position attribute and set it to a position with a computed value. Example: { lat: 42.345573, lng: -71.098326 }
+
+    <google-streetview-pano
+      position="[[_myComputedPosition()]]"
+      heading="330"
+      pitch="-2"
+      zoom="0.8"
+      disable-default-ui>
+    </google-streetview-pano>
+
 @demo
 -->
 
 <dom-module id="google-streetview-pano">
   <style>
     :host {
       display: block;
     }
     #pano {
       height: 100%;
     }
   </style>
   <template>
     <google-maps-api api-key="{{apiKey}}" version="{{version}}"
-                     libraries="{{libraries}}"
                      client-id="{{clientId}}"
                      language="{{language}}"
                      client
                      on-api-load="_mapApiLoaded"></google-maps-api>
     <div id="pano" on-mouseenter="_autoStop"
                    on-mouseleave="_autoUpdate"></div>
   </template>
 </dom-module>
 
 <script>
   "use strict";
 
   Polymer({
+
     is: 'google-streetview-pano',
-      properties: {
+
+    properties: {
       /**
        * A Maps API key. To obtain an API key, see developers.google.com/maps/documentation/javascript/tutorial#api_key.
        */
       apiKey: String,
 
       /**
        * A Maps API for Business Client ID. To obtain a Maps API for Business Client ID, see developers.google.com/maps/documentation/business/.
        * If set, a Client ID will take precedence over an API Key.
        */
       clientId: String,
 
       /**
        * The localized language to load the Maps API with. For more information
        * see https://developers.google.com/maps/documentation/javascript/basics#Language
        *
        * Note: the Maps API defaults to the preferred language setting of the browser.
        * Use this parameter to override that behavior.
        *
        */
       language: String,
 
       /**
-       * A comma separated list (e.g. "places,geometry") of libraries to load
-       * with this map. Defaults to "places". For more information see
-       * https://developers.google.com/maps/documentation/javascript/libraries.
-       *
-       */
-      libraries: {
-        type: String,
-        value: "places"
-      },
-
-      /**
        * Version of the Google Maps API to use.
        *
        */
       version: {
         type: String,
         value: '3.exp'
       },
 
       /**
        * Specifies which photosphere to load
        *
-       * **Required**
+       *
        */
       panoId: {
         type: String,
         observer: '_panoIdChanged'
       },
 
       /**
+       * Specifies which position to load
+       *
+       *
+       */
+      position: {
+        type: Object,
+        observer: '_positionChanged'
+      },
+
+      /**
        * The camera heading in degrees relative to true north. True north is 0°, east is 90°, south is 180°, west is 270°.
        */
       heading: {
         type: Number,
         value: 45
       },
 
       /**
        * The camera pitch in degrees, relative to the street view vehicle. Ranges from 90° (directly upwards) to -90° (directly downwards).
        */
@@ skipping 17 matching lines @@
         type: Boolean,
         value: false
       },
 
       /**
        * If true, disables the auto panning animation
        */
       disableAutoPan: {
         type: Boolean,
         value: false
-      },
+      }
 
     },
 
     pano: null,
     rAFid: null,
+
+    /**
+     * Called when the Google Maps API has loaded.
+     */
     _mapApiLoaded: function() {
-      this.pano = new google.maps.StreetViewPanorama(
-          this.$.pano,
-          this._getPanoOptions());
+      this.pano = new google.maps.StreetViewPanorama(this.$.pano, this._getPanoOptions());
       this.pano.setVisible(true);
 
       if (this.disableAutoPan) {
         return;
       }
       // Kickoff the rotating animation
       this.rAFid = requestAnimationFrame(this.update.bind(this));
     },
 
     /**
      * Returns the an object with the current panorama configurations.
      */
     _getPanoOptions: function() {
       var panoOptions = {
         pano: this.panoId,
+        position: this.position,
         pov: {
           heading: this.heading,
           pitch: this.pitch
         },
         disableDefaultUI: this.disableDefaultUi,
         zoom: this.zoom
       };
 
       return panoOptions;
     },
@@ skipping 42 matching lines @@
       }
 
       this.stop();
     },
 
     _panoIdChanged: function(newVal, oldVal) {
       if (this.pano) {
         this.pano.setPano(newVal);
         this.reset();
       }
+    },
+
+    _positionChanged: function(newVal, oldVal) {
+      if (this.pano) {
+        this.pano.setPosition(newVal);
+        this.reset();
+      }
     }
   });
 </script>