fix hangup and refer task

lib/tasks/cognigy/index.js

@@ -285,7 +285,7 @@ class Cognigy extends Task {
               this.performAction({cognigyResult: 'refer succeeded'});
               this.reportedFinalAction = true;
               cs.replaceApplication([{'sip:refer': {
-                referTo: number,
+                referTo: evt.data.number,
                 referredBy: 'cognigy'
               }}]);
             }).bind(this));