Add hung bots to sheriff-o-matic view

Tools/GardeningServer/model/ct-sheriff-failure-group-data.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-commit-list.html">
 
 <script>
 function CTSheriffFailureGroupData(failures, commitList) {
   this.failures = failures;
   this.commitList = commitList;
-  this.type = 'sheriff';
+  this.category = 'sheriff';
 };
 
 CTSheriffFailureGroupData.prototype.getAnnotations = function() {
   return this.failures.map(function(failure) {
     return failure.annotations();
   }).flatten();
 };
 
 CTSheriffFailureGroupData.prototype.dataToExamine = function() {
   return this.failures;
 };
 
 CTSheriffFailureGroupData.prototype.failureKeys = function() {
   return this.failures.map(function(failure) {
     return failure.keys();
   }).flatten();
 };
 </script>