add x-reason to sip-decline (#1518)

* add x-ver to sip-decline

* lint

* Update sip_decline.js

---------

Co-authored-by: Dave Horton <daveh@beachdognet.com>

lib/tasks/sip_decline.js

@@ -17,7 +17,7 @@ class TaskSipDecline extends Task {
   async exec(cs, {res}) {
     super.exec(cs);
     res.send(this.data.status, this.data.reason, {
-      headers: this.headers
+      headers: {'X-Reason': 'SIP Decline Verb', ...this.headers}
     }, (err) => {
       if (!err) {
         // Call was successfully declined