Updated bower.
- Notes:

1. Ember does not support handlebars v2.0.0 until v1.9.0
http://emberjs.com/blog/2014/10/16/handlebars-update.html

2. Ember got bugged, so updated Ember Data to compatible version.
http://stackoverflow.com/questions/26086667/ember-data-cannot-read-property-async-of-undefined

Removed belongsTo relationship loading on server.
Ember only requires Id's, so fetching of belongsTo relationships is not necessary.
Refactored serializer.

Created Model component in Ember which all models can derive from.