add retries for pinging function

backend:
- new field for monitor: maxretries
- new pending status while service is retrying: 2
- pending status event is not marked important
- pending pings however register as downtime in the calculation

frontend:
- added pending status while service is retrying
- added color for new pending status
- added field to configure amount of retries

database:
- IMPORTANT: THIS REQUIRES MIGRATION!!!!
- added field: maxretries with default value 0

src/components/HeartbeatBar.vue

@@ -3,7 +3,7 @@
         <div class="hp-bar-big" :style="barStyle">
             <div
                 class="beat"
-                :class="{ 'empty' : (beat === 0), 'down' : (beat.status === 0) }"
+                :class="{ 'empty' : (beat === 0), 'down' : (beat.status === 0), 'pending' : (beat.status === 2) }"
                 :style="beatStyle"
                 v-for="(beat, index) in shortBeatList"
                 :key="index"
@@ -166,6 +166,10 @@ export default {
             background-color: $danger;
         }
 
+        &.pending {
+            background-color: $warning;
+        }
+
         &:not(.empty):hover {
             transition: all ease-in-out 0.15s;
             opacity: 0.8;