don't auto-update on some local-only operations

There are some local-only operations (getting help, messing with services) that can't be done when you're without connectivity, since boxen will attempt to auto-update itself first. There's actually a `--no-pull` arg, but it's hard to know about that since you can't even get the help without auto-updating.

So this turns off auto-updating for help and for enabling/disabling/restarting services.

This will fix boxen/boxen#95 if accepted.

Also, let's not talk at all about how I accidentally committed these to master before pulling back and making this PR. It never happened.