title: How to get meteor.com apps to use external mongo db
body: <p>On my dev machine I can set the environment variable MONGO_URL to define the mongo instance I want my app to use. How to I set the mongo instance that my app on meteor.com will use?</p>
  
  <p>I'm looking for something I could put in my settings.json, or some other way to set MONGO_URL for my meteor app at myapp.meteor.com</p>