Fix continuous suspension of the timeago alerts

The default hearbeat-setting is 60 seconds, so the delta between two
timeago-checks will always be >15 seconds and the timeago-alarms will
always be suspended (that's what Papertrail also shows).

To fix this, make the delta-check heartbeat-setting-dependant and also simplify
the code by using just 1 variable.

lib/plugins/timeago.js

@@ -3,10 +3,10 @@
 var levels = require('../levels');
 var times = require('../times');
 var lastChecked = new Date();
-var lastSuspendTime = new Date("1900-01-01");
 
 function init(ctx) {
   var translate = ctx.language.translate;
+  var heartbeatMs = ctx.settings.heartbeat * 1000;
 
   var timeago = {
     name: 'timeago',
@@ -64,21 +64,14 @@ function init(ctx) {
   };
 
   timeago.checkStatus = function checkStatus(sbx) {
-
     // Check if the app has been suspended; if yes, snooze data missing alarmn for 15 seconds
     var now = new Date();
     var delta = now.getTime() - lastChecked.getTime();
     lastChecked = now;
 
-    if (delta > 15 * 1000) { // Looks like we've been hibernating
-      lastSuspendTime = now;
-    }
-
-    var timeSinceLastSuspended = now.getTime() - lastSuspendTime.getTime();
-
-    if (timeSinceLastSuspended < (10 * 1000)) {
-
-      console.log('Hibernation detected, suspending timeago alarm');
+    // More than 2 heartbeats since last call: looks like we've been hibernating
+    if (delta > 2 * heartbeatMs) {
+      console.log('Hibernation detected because of 2 missed hearbeats, suspending timeago alarm. heartbeatMs:', heartbeatMs, 'delta:', delta);
       return 'current';
     }