Fix/193 (#195)

* pass sip failure reason back to FS

* Update call-session.js

* update drachtio-srf dep

lib/call-session.js

@@ -642,7 +642,7 @@ class CallSession extends Emitter {
               }, this.decrKey, {writeCallCountSP, writeCallCount, writeCallCountApp})
                 .catch((err) => this.logger.error(err, 'Error decrementing call counts'));
             }
-            debug(`got final outdial error: ${err}`);
+            this.logger.debug(`got final outdial error: ${err}`);
             if (!passFailure) this.res.send(status);
             this.emit('failed');
             this.rtpEngineResource.destroy()