Tweak mail templates a bit, to reference config values

probably more needs to be done, this is at least a step..

rattail_tempmon/templates/mail/tempmon_error.html.mako

@@ -4,7 +4,7 @@
     <p>At ${taken or now}, ${probe} reported that its status was: ${status}.<br>
       Something went wrong. Please investigate as soon as possible.
     </p>
-    <p>This email will repeat every 15 minutes until the issue is resolved.
+    <p>This email will repeat every ${probe.status_alert_timeout} minutes until the issue is resolved.
     </p>
   </body>
 </html>