Allow pluralization to be configurable.

To customize provide a `pluralizedTypes` object to your extended
version of the Resolver:

```javascript
import Resolver from 'ember/resolver';

export default Resolver.extend({
  pluralizedTypes: {
   'sheep': 'sheep'
   'config': 'config'
  }
})
```
Update dist/.
Merge pull request #68 from rwjblue/pluralization

Allow pluralization to be configurable.