Add option to disable webpack dev server livereload

Add option to disable webpack dev server livereload

• Livereload defaults to true
• Disable livereload: echo false > webpack_livereload

After setting the webpack_livereload file -> gdk reconfigure to regenerate the Procfile ->Restart the app gdk run

See https://gitlab.com/gitlab-org/gitlab-ce/issues/28204

MR on CE to pickup the DEV_SERVER_LIVERELOAD environment variable: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9287

cc @mikegreiling

assigned to @jacobvosmaer-gitlab

Thanks @MadLittleMods . Just for my understanding, what exactly do we need the webpack_livereload file for? Could the user just edit their Procfile?

@jacobvosmaer-gitlab Yes. It seems like this is the way settings are being handled atm (followed suit from webpack_port) and this lives beyond a gdk reconfigure.

Closed because of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9287#note_23738483

closed