config.js

new Demo({
  hosts: {
    production: ['forms.meteor.com']
  },
  github: {
    user: 'possibilities',
    repo: 'meteor-forms'
  }
});

env.js

Demo.prototype._establishEnv = function() {
  Meteor.env || (Meteor.env = {});

  if (Meteor.is_client) {
    if (this.hosts && this.hosts.production) {
      var isProductionHost = _.contains(this.hosts.production, window.location.hostname);

      Meteor.env.is_development = !isProductionHost;
      Meteor.env.is_production = isProductionHost;
    } else {
      return console.log("You have to provide a list of production hosts for this to work on the client!");
    }
  } else {
    var path = __meteor_bootstrap__.require('path');
    var pathToConfig = process.env.HOME + '/.meteor.cfg';

    var configExists = path.existsSync(pathToConfig);
    Meteor.env.is_development = configExists;
    Meteor.env.is_production = !configExists;
  }

};