Adds a snooze button to the sheriff-o-matic ui

Tools/GardeningServer/ui/ct-failure-stream.html

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <link rel="import" href="ct-failure-card.html">
 
 <polymer-element name="ct-failure-stream" attributes="groups commits tree" noscript>
   <template>
     <style>
       :host {
         display: block;
       }
 
       ct-failure-card {
         margin: 5px;
         padding: 5px;
         border-top: 1px solid lightgrey;
       }
     </style>
-    <template repeat="{{failures in groups}}">
-      <ct-failure-card failures="{{ failures }}" commits="{{ commits }}" tree="{{ tree }}"></ct-failure-card>
+    <template repeat="{{ group in groups }}">
+      <ct-failure-card group="{{ group }}" commits="{{ commits }}" tree="{{ tree }}"></ct-failure-card>
     </template>
   </template>
 </polymer-element>