Add vagrant chassis command with helpers

[rmccue]

It would be great if we could have some custom Chassis CLI commands. Something like:

• vagrant chassis
  • config - Prints merged configuration for the current project.
  • extensions
    • add {name|url} - Add extension by name/URL
    • remove {name} - Remove extension
  • debug - Maybe a helper for troubleshooting?

Maybe more too!

[BronsonQuick]

I'll dump a couple of examples of things that might be nice for the debug command:

1. Sometimes avahi stops working on the box and the url doesn't resolve in the browser: sudo service avahi-daemon restart can fix this. We can check the status with service avahi-daemon status
2. Sometimes an install will fail and give a 255 error. This often tends to be caused by PHP throwing errors. We could try and toggle on error reporting and running the command again to see if that works. We could maybe grep the logs/php output for fatals. A few ways to replicate this could be having missing files in require_once or a dodgy setup of Memcache(d).