feat(controller): support as instance syntax

Support `ng-controller="MyController as my"` syntax
which publishes the controller instance to the
current scope.

Also supports exporting a controller defined with route:
````javascript
angular.module('routes', [], function($routeProvider) {
  $routeProvider.when('/home', {controller: 'Ctrl as home', templateUrl: '...'});
});
````


## I think we should change the docs to recommend only single way of doing this.