core(controller.has): Add a public "has" method to the Controller class, to check the existence of a given controller.

Author: Vadorequest

src/ng/controller.js

@@ -27,6 +27,15 @@ function $ControllerProvider() {
   var controllers = {},
       globals = false;
 
+  /**
+   * @ngdoc method
+   * @name $controllerProvider#has
+   * @param (string) name Controller name to check.
+   */
+  this.has = function(name){
+    return (name && controllers[name])? true : false;
+  };
+
   /**
    * @ngdoc method
    * @name $controllerProvider#register