make alert protractor testable

Basicall using the `$interval` module. More details: angular/protractor#169 (comment)

src/alert/alert.js

@@ -19,12 +19,13 @@ angular.module('ui.bootstrap.alert', [])
   };
 })
 
-.directive('dismissOnTimeout', ['$timeout', function($timeout) {
+.directive('dismissOnTimeout', ['$interval', function($interval) {
   return {
     require: 'alert',
     link: function(scope, element, attrs, alertCtrl) {
-      $timeout(function(){
+      var intervalCanceller = $interval(function() {
         alertCtrl.close();
+        $interval.cancel(intervalCanceller);
       }, parseInt(attrs.dismissOnTimeout, 10));
     }
   };

src/alert/test/dismissOnTimeout.spec.js

@@ -1,21 +1,21 @@
 describe('dismissOnTimeout', function () {
 
-  var scope, $compile, $timeout;
+  var scope, $compile, $interval;
 
   beforeEach(module('ui.bootstrap.alert'));
   beforeEach(module('template/alert/alert.html'));
-  beforeEach(inject(function ($rootScope, _$compile_, _$timeout_) {
+  beforeEach(inject(function ($rootScope, _$compile_, _$interval_) {
     scope = $rootScope;
     $compile = _$compile_;
-    $timeout = _$timeout_;
+    $interval = _$interval_;
   }));
 
   it('should close automatically if auto-dismiss is defined on the element', function () {
     scope.removeAlert = jasmine.createSpy();
     $compile('<alert close="removeAlert()" dismiss-on-timeout="500">Default alert!</alert>')(scope);
     scope.$digest();
 
-    $timeout.flush();
+    $interval.flush();
     expect(scope.removeAlert).toHaveBeenCalled();
   });
 });