Feature/incoming refer (#76)

* Dial: handle incoming REFER on either leg by calling referHook, if configured

* lint

* modify payload of referHook

* support target.trunk on rest createCall api

* bugfix: gather partial result hook was not working

* lint

* handling of incoming REFER

lib/tasks/sip_decline.js

@@ -19,7 +19,11 @@ class TaskSipDecline extends Task {
     res.send(this.data.status, this.data.reason, {
       headers: this.headers
     });
-    cs.emit('callStatusChange', {callStatus: CallStatus.Failed, sipStatus: this.data.status});
+    cs.emit('callStatusChange', {
+      callStatus: CallStatus.Failed,
+      sipStatus: this.data.status,
+      sipReason: this.data.reason
+    });
   }
 }