Fix bower.json dependencies.

Ember-data is a dependency at runtime, not just a devDependency.

I noticed this because my build tool, [Brunch](http://brunch.io), builds a dependency graph for concatenating Bower components in the right order. Ember Data needs to be listed as a dependency for it to be included before EmberData.model-fragments.
Handlebars is included by the ember ```bower.json```