Serve command: Bind to 0.0.0.0

Change the `artisan serve` command to bind the server to 0.0.0.0 instead of localhost.  This allows other machines to connect to the server which is useful if using a gui-less VM or in a team situation to demo changes.

It might be worth putting this behind an option (`--any-host` for example) and still defaulting to localhost for security but thought I'd open it up for discussion.