feat(carousel): expose carousel controller via controllerAs

- Expose the carousel controller in the component via `controllerAs`

Closes #4131

src/carousel/carousel.js

@@ -249,6 +249,7 @@ angular.module('ui.bootstrap.carousel', [])
     transclude: true,
     replace: true,
     controller: 'CarouselController',
+    controllerAs: 'carousel',
     require: 'carousel',
     templateUrl: 'template/carousel/carousel.html',
     scope: {

src/carousel/test/carousel.spec.js

@@ -457,5 +457,22 @@ describe('carousel', function() {
         expect(scope.next.calls.count()).toBe(1);
       });
     });
+
+    it('should be exposed in the template', inject(function($templateCache) {
+      $templateCache.put('template/carousel/carousel.html', '<div>{{carousel.text}}</div>');
+
+      var scope = $rootScope.$new();
+      var elm = $compile('<carousel interval="bar" no-transition="false" no-pause="true"></carousel>')(scope);
+      $rootScope.$digest();
+
+      var ctrl = elm.controller('carousel');
+
+      expect(ctrl).toBeDefined();
+
+      ctrl.text = 'foo';
+      $rootScope.$digest();
+
+      expect(elm.html()).toBe('foo');
+    }));
   });
 });