Do not display slotrefs for unreservable slots

Stop displaying slot reference codes in the "additional tracks"
table if the slot is actually not bookable

Change-Id: I367d75bcfc289475d28df2bbd524adda059f4b05

html/ptg.html

@@ -114,7 +114,7 @@
       {{#if (lookup schedule time.name)}}
       <td><span class="label label-primary {{lookup schedule time.name}}">{{lookup schedule time.name}}</td>
       {{else}}
-      <td><small><i>{{room}}-{{time.name}}</i></small></td>
+      <td><small><i>{{roomcode schedule room time.name}}</i></small></td>
       {{/if}}
       {{/each}}
      </tr>

html/ptg.js

@@ -18,6 +18,13 @@ Handlebars.registerHelper('hashtag', function(options) {
   return new Handlebars.SafeString(sentence);
 });
 
+Handlebars.registerHelper('roomcode', function(schedule, room, timecode) {
+  if (schedule[timecode] == "") {
+    return room + "-" + timecode;
+  }
+  return "";
+});
+
 // What is the day today ?
 var now = new Date();
 var days = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'];