feat(directive): support as instance syntax

Support controller: 'MyController as my' syntax for directives which publishes
the controller instance to the directive scope.

Support controllerAs syntax to define an alias to the controller within the
directive scope.

Author: lgalfaso

test/ng/compileSpec.js

@@ -2244,7 +2244,7 @@ describe('$compile', function() {
     });
 
 
-    iit('should support controllerAs', function() {
+    it('should support controllerAs', function() {
       module(function() {
         directive('main', function() {
           return {