Display public room topics if they exist on the public room list.

webclient/app.css

@@ -276,6 +276,13 @@ a:active  { color: #000; }
     float: right;
 }
 
+.publicRoomTopic {
+    color: #888;
+    font-size: 12px;
+    padding-right: 5px;
+    float: right;
+}
+
 #roomName {
     font-size: 16px;
     text-align: right;

webclient/home/home.html

@@ -34,6 +34,9 @@
             ng-show="room.num_joined_members">
                 {{ room.num_joined_members }} {{ room.num_joined_members == 1 ? 'user' : 'users' }}
             </div>
+            <div class="publicRoomTopic" ng-show="room.topic">
+                {{ room.topic }}
+            </div>
         </div>
     </div>
     <br/>