Allow a per-jobset check interval

This allows checking a jobset (say) at most once a day.  It's also
possible to disable polling by setting the interval to 0.  This is
useful for jobsets that use push notification or are manually
evaluated.

src/root/edit-jobset.tt

@@ -83,6 +83,17 @@
       </div>
     </div>
 
+    <div class="control-group">
+      <label class="control-label">Check interval</label>
+      <div class="controls">
+        <div class="input-append">
+          <input type="number" class="span3" name="checkinterval" [% HTML.attributes(value => jobset.checkinterval) %]></input>
+          <span class="add-on">sec</span>
+        </div>
+        <span class="help-inline">(0 to disable polling)</span>
+      </div>
+    </div>
+
     <div class="control-group">
       <div class="controls">
         <label class="checkbox">

src/root/jobset.tt

@@ -120,6 +120,10 @@
         <th>Enabled:</th>
         <td>[% jobset.enabled ? "Yes" : "No" %]</td>
       </tr>
+      <tr>
+        <th>Check interval:</th>
+        <td>[% jobset.checkinterval || "<em>disabled</em>"  %]</td>
+      </tr>
       <tr>
         <th>Enable email notification:</th>
         <td>[% jobset.enableemail ? "Yes" : "No" %]</td>