Feature/vm detection (#137)

* initial changes for amd

* wip

* fix bug where transcripts were discarded

* a bit of refactoring, and adding support for avmd in config verb

* bug fixes

lib/session/call-session.js

@@ -72,6 +72,10 @@ class CallSession extends Emitter {
 
     if (!this.isConfirmCallSession && !this.isSmsCallSession && !this.isAdultingCallSession) {
       sessionTracker.add(this.callSid, this);
+
+      const {startAmd, stopAmd} = require('../utils/amd-utils')(logger);
+      this.startAmd = startAmd;
+      this.stopAmd = stopAmd;
     }
 
     this._pool = srf.locals.dbHelpers.pool;