gateway config via config files

[muhamadazmy]

To be able to safely restart or update the webgw without losing active configuration. I suggest that the GW also support watching a config directory where we can maintain a file per proxy configuration (regardless of the name of the file).

Operation on the directory (add a new file, delete or update) should trigger the GW to reload its config.

This will make sure if the gw was restarted or updated that old config (done before the restart) are effective immediately.