Feature/queue webhooks (#34)

* initial changes for queue webhooks

* send queue leave webhook when dequeued

* bugfix: if enqeue task is killed because it is being replaced with new app supplied by LCC, ignore any app returned from the actionHook as LCC takes precedence

* remove leftover merge brackets

lib/utils/constants.json

@@ -92,6 +92,10 @@
     "Hangup": "hangup",
     "Timeout": "timeout"
   },
+  "KillReason": {
+    "Hangup": "hangup",
+    "Replaced": "replaced"
+  },
   "MAX_SIMRINGS": 10,
   "BONG_TONE": "tone_stream://v=-7;%(100,0,941.0,1477.0);v=-7;>=2;+=.1;%(1400,0,350,440)"
 }