Removed Bacbone.sync override

[davideast]

Prior to the 0.4 release a new Backbone.Mode could be created with a firebase attribute.

var Todo = Backbone.Model.extend({
   firebase: 'https://<your-firebase>.firebaseio.com/'
});

This behavior is being removed in the 0.4 release. The reasoning behind this decision was due to the confusion of the separate components: Backbone.Firebase.Model and Backbone.Model.extend({ firebase: ''});

Going forward all of the functionality BackFire provides will be in the Backbone.Firebase namespace. There will still be an option that allows for data to not automatically be synced. In those cases you will be able to call sync(), save(), fetch(), and etc...

This will leave the core of Backbone untouched, while hopefully reducing confusion.

[coveralls]

Coverage decreased (-1.44%) when pulling a2f78c4 on remove-sync-override into 3235f53 on 0.4-release.