Proper `exports` signature

[ryanflorence]

Maybe I don't know about some AMD spec or implementation out there that uses __exports__, but the signature for using exports and module is such (see https://github.com/amdjs/amdjs-api/wiki/AMD):

define('app', ['require', 'exports', 'module'], function(require, exports, module) {
  // everything else in here is identical to commonjs
  // local require is synchronous, so anything required has to be loaded already.
  var Ember = require('ember');
  module.exports = Ember.Application.create();
});

Doing it this way will allow folks to use the r.js optimizer in conjunction with this library for sweet ES6 module bliss.

[wycats]

I thought that you could use whatever parameter you want as long as the dependency string was "exports"