Alert pulse tweak (grafana#6508)

* Added faint tint of red to alerting panels, started working on animation. more to come

* Finally happy with pulse animation. Ready to merge

Author: mattttt

public/sass/pages/_alerting.scss

@@ -50,7 +50,9 @@
 
 .panel-alert-state {
   &--alerting {
-    animation: alerting-panel 2s 0s infinite;
+    background-color: mix($critical,$panel-bg, 3%);
+    animation: alerting-panel 1.6s cubic-bezier(1,.1,.73,1) 0s infinite alternate;
+    box-shadow: 0 0 10px rgba($critical,0.5);
     opacity: 1;
 
     .panel-alert-icon:before {
@@ -69,15 +71,7 @@
 }
 
 @keyframes alerting-panel {
-  0% {
-    box-shadow: none;
-  }
-  50% {
-    box-shadow: 0 0 10px $critical;
-  }
   100% {
-    box-shadow: none;
+    box-shadow: 0 0 15px $critical;
   }
 }
-
-

public/sass/pages/_dashboard.scss

@@ -212,5 +212,3 @@ div.flot-text {
     padding: 0.5rem .5rem .2rem .5rem;
   }
 }
-
-