This check & `msg.send` are duplicated in each of the commands. I'd suggest moving it to a helper like `validEnvironment` like:

```coffeescript
validEnvironment = (msg) ->

   if process.env.HUBOT_AIRTIME_URL
     true
   else
      msg.send "Please set the HUBOT_AIRTIME_URL environment variable."
      false
```

That would simplify the other commands to like: `return unless validEnvironment(msg)`.