EmberAddon

Will call the EmberApp constructor with defaults for addon projects. In
the addons Brocfile only the following is required:

```js
var EmberAddon = require('ember-cli/lib/broccoli/ember-addon');
var addon = new EmberAddon();
module.exports = addon.toTree();
```
Improve regex for finding existing routes
Allow addons to be vendored outside of node modules

In package.json you can add paths for additional addons

```json
"ember-addon": {
  "paths": [
    "./lib/super-button"
  ]
}
```

The vendored library must conform to the addon spec, so it must have a
properly declared `package.json` file as well as its own loader.
Add verbose option to version command
Add test for version command.