Show avatar at top right in account-dropdown button

* When avatars are enabled, show it instead of full name.
* Port away from 'gr-ajax' for getting server config.
* Cleanup 'gr-rest-api-interface' test a bit.

Change-Id: Ib735a4efee4dd4386885693bc30b55f73a813ec7

polygerrit-ui/app/elements/change/gr-message/gr-message.html

diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.html b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
index 5733acd..7c287db 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.html
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.html
@@ -19,6 +19,7 @@
 <link rel="import" href="../../shared/gr-button/gr-button.html">
 <link rel="import" href="../../shared/gr-date-formatter/gr-date-formatter.html">
 <link rel="import" href="../../shared/gr-linked-text/gr-linked-text.html">
+<link rel="import" href="../../shared/gr-rest-api-interface/gr-rest-api-interface.html">
 
 <link rel="import" href="../gr-comment-list/gr-comment-list.html">
 
@@ -120,6 +121,7 @@
         <gr-button small on-tap="_handleReplyTap">Reply</gr-button>
       </div>
     </div>
+    <gr-rest-api-interface id="restAPI"></gr-rest-api-interface>
   </template>
   <script src="gr-message.js"></script>
 </dom-module>

polygerrit-ui/app/elements/change/gr-message/gr-message.js

diff --git a/polygerrit-ui/app/elements/change/gr-message/gr-message.js b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
index 1ab5e6c..26b9fb9 100644
--- a/polygerrit-ui/app/elements/change/gr-message/gr-message.js
+++ b/polygerrit-ui/app/elements/change/gr-message/gr-message.js
@@ -57,7 +57,7 @@
     },
 
     ready: function() {
-      app.configReady.then(function(cfg) {
+      this.$.restAPI.getConfig().then(function(cfg) {
         this.showAvatar = !!(cfg && cfg.plugin && cfg.plugin.has_avatars) &&
             this.message && this.message.author;
       }.bind(this));