WIP: Updated () to return a promise

Author: jwngr

src/FirebaseAuth.js

@@ -139,7 +139,9 @@
      */
     signOut: function() {
       if (this.getAuth() !== null) {
-        this._auth.signOut();
+        return this._q.when(this._auth.signOut());
+      } else {
+        return this._q.when();
       }
     },
 

tests/unit/FirebaseAuth.spec.js

@@ -310,6 +310,10 @@ describe('FirebaseAuth',function(){
   });
 
   describe('$signOut()',function(){
+    it('should return a promise', function() {
+      expect(authService.$signOut()).toBeAPromise();
+    });
+
     it('will call signOut() on backing auth instance when user is signed in',function(){
       spyOn(authService._, 'getAuth').and.callFake(function () {
         return {provider: 'facebook'};