Fix/transport in contact (#190)

* use the req transport param in the From and Contact headers if set.

* Update call-session.js

lib/call-session.js

@@ -497,16 +497,19 @@ class CallSession extends Emitter {
           };
         }
         else {
+          const uri = parseUri(this.req.uri);
           hdrs = {
             ...hdrs,
             'From': createBLegFromHeader({
               logger: this.logger,
               req: this.req,
+              transport: uri.params.transport,
               ...(private_network && {host: this.privateSipAddress})
             }),
             'Contact': createBLegFromHeader({
               logger: this.logger,
               req: this.req,
+              transport: uri.params.transport,
               ...(private_network && {host: this.privateSipAddress})
             })
           };