Restore tunnel for BrowseSync server

Summary:
0950c4aa2dec introduced a tunnel option through localtunnel service,
but it has then been removed during a build workflow upgrade.

This is a follow-up for 23dad25dfd0a.

Test Plan: npm start returns well Tunnel: https://serverslog.loca.lt

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2931