added support for controllerAs with function variables instead of string

This is needed in addition to the `"MyController as vm"` syntax because I need to reference the controller as a function instead of a string. This is not possible currently. 

Now, by setting `controllerAs` in the state it will work. `$stateProvider.state("name", {url:"/url", controller: MyController, controllerAs:"vm"})`

This brings it in line with how angular-router works too. 

https://github.com/angular/angular.js/blob/master/src/ngRoute/directive/ngView.js#L263