Require wrapping addon/routes.js default export to allow upgradability.

[rwjblue]

As we learned the hard way in the Ember 1.x series, having plain functions being exported can become quite painful from a compatibility perspective. I would prefer to avoid the mistakes we made with Handlebars helpers, and require that the routes file be wrapped in a helper function so that we have a way to handle compatibility concerns with any future refactors.

import buildRoutes from 'ember-engines/routes';

export default buildRoutes(function() {
  this.route('foo');
  this.route('bar');
});

[rwjblue]

@dgeb - Do the above import paths and names look OK to you?

[dgeb]

Do the above import paths and names look OK to you?

@rwjblue yeah, that looks good to me.

I agree this is an important change that we should make before releasing v0.2.0

[dgeb]

Closed via #73