angularFireResource + firebase directive

Demo:  http://jsfiddle.net/ItsLeeOwen/Xapq4/

Reason For Additions:
 - Declarative directive syntax to interface w/ firebase.
 - A service where $scope is optional
 - Explicit controls where the scope target-reference could be either a collection or an object.

Added:
 - "angularFireResource" service.
 - "firebase" directive built on angularFireResource service.

Directive:  Super simple declarative syntax for getting firebase data into your angularJS apps.

Example: 
<div firebase
  domain="https://YOURFIREBASE.firebaseio.com" 
  location="path/to/your/stuff">
    <div ng-repeat="thing in stuff">
      <input type="text" ng-model="thing.value" />
    </div>
</div>

Service: Support for a variety of ways of integrating firebase data into your client app, including explicit control that is compatible with either a collection or object snapshot value.

Example 1:
angularFireResource(
        'https://lee.firebaseio.com/gizmos', 
        $scope,
        'gizmos'
    );

Example 2:
angularFireResource(
        'https://lee.firebaseio.com/gizmos', 
        $scope,
        []
    );

Example 3:
    var resource = angularFireResource(
        'https://YOURFIREBASE.firebaseio.com/stuff'
    );
    resource.promise.then(function(stuff) {
        $scope.stuff = stuff;
        $scope.$watch('stuff', function(value) {
            resource.set(value);
        }, true);
    });

Example 4:
$scope.data = {}
angularFireResource(
        'https://lee.firebaseio.com/gizmos', 
        null,
        $scope.data
    );