[BUGFIX release] Ensure exports are setup for node build.

With this you can more easily use the Ember object system in node.

Generate with `npm run build`.

Then you can run the following in a `node` REPL:

```javascript
Ember = require('./dist/ember-runtime');

var Person = Ember.Object.extend({
  firstName: null,
  lastName: null,
  fullName: Ember.computed('firstName', 'lastName', function() {
    return this.get('lastName') + ', ' + this.get('firstName');
  })
});

var max   = Person.create({ firstName: 'Max', lastName: 'Jackson'});
var james = Person.create({ firstName: 'James', lastName: 'Jackson'});

max.get('fullName'); //=> Jackson, Max
james.get('fullName'); //=> Jackson, James
````