fix(*): Closes #143 - introduce deepCopy option to support deep copy on draggable/droppable

  Deep Copy basically looses prototypical inheritence which is sometimes necessary and hence it is made optional via deepCopy option.
  More Info: https://egghead.io/lessons/angularjs-angular-copy-for-deep-copy

Author: codef0rmerz

README.md

@@ -35,6 +35,7 @@ angular.module('myApp', ['ngDragDrop'])
     * **onDrag** – string – callback method to be invoked while the mouse is moved during the dragging
     * **applyFilter** - string - applies AngularJS $filter on the list before swapping items. Only applicable, if ngRepeat has any filter (such as orderBy, limitTo) associated with it.
     * **containment** – string - position/offset. Offset by default. This forces to use jQuery.position() or jQuery.offset() to calculate proper position with respect to parent element or document respectively. 
+    * **deepCopy** - boolean (optional) – If true, makes a deep copy of draggable that looses prototypical inheritance.
 * **data-drag** – boolean – If true, element can be draggable. Disabled otherwise.
 * **data-jqyoui-options** – object – should hold all the valid options supported by [jQueryUI Draggable](http://api.jqueryui.com/draggable)
 * **ng-model** – string – An angular model defined in a controller. Should be a JS array or object
@@ -49,6 +50,7 @@ angular.module('myApp', ['ngDragDrop'])
     * **onOut** – string – callback method to be invoked when an accepted draggable is dragged out of the droppable
     * **applyFilter** - string - requires if both droppable as well as draggable share the same ngModel.
     * **containment** – string - position/offset. Offset by default. This forces to use jQuery.position() or jQuery.offset() to calculate proper position with respect to parent element or document respectively. 
+    * **deepCopy** – boolean (optional) – If true, makes a deep copy of droppable that looses prototypical inheritance.
 * **data-drop** – boolean – If true, element can be droppable. Disabled otherwise.
 * **data-jqyoui-options** – object – should hold all the valid options supported by [jQueryUI Droppable](http://api.jqueryui.com/droppable)
 * **ng-model** – string – An angular model defined in a controller. Should be a JS array or object.
@@ -63,6 +65,11 @@ angular.module('myApp', ['ngDragDrop'])
 ##Demo
 Demo is [here](http://codef0rmer.github.io/angular-dragdrop/#/)
 
+
+###v1.0.9 - breaking change
+Draggable and Droppable will not be deep copied by default unlike previous versions. Use deepCopy option, if needed.
+
+
 ###v1.0.5 - breaking change
 Do not pass evaluated expressions in callbacks. For example, 
 ####Before:

src/angular-dragdrop.js

@@ -88,7 +88,11 @@ var jqyoui = angular.module('ngDragDrop', []).service('ngDragDropService', ['$ti
       dropSettings.index = this.fixIndex(droppableScope, dropSettings, dropModelValue);
 
       jqyoui_pos = angular.isArray(dragModelValue) ? dragSettings.index : null;
-      dragItem = angular.copy(angular.isArray(dragModelValue) ? dragModelValue[jqyoui_pos] : dragModelValue);
+      dragItem = angular.isArray(dragModelValue) ? dragModelValue[jqyoui_pos] : dragModelValue;
+
+      if (dragSettings.deepCopy) {
+        dragItem = angular.copy(dragItem);
+      }
 
       if (angular.isArray(dropModelValue) && dropSettings && dropSettings.index !== undefined) {
         dropItem = dropModelValue[dropSettings.index];
@@ -97,7 +101,10 @@ var jqyoui = angular.module('ngDragDrop', []).service('ngDragDropService', ['$ti
       } else {
         dropItem = {};
       }
-      dropItem = angular.copy(dropItem);
+
+      if (dropSettings.deepCopy) {
+        dropItem = angular.copy(dropItem);
+      }
 
       if (dragSettings.animate === true) {
         this.move($draggable, $droppableDraggable.length > 0 ? $droppableDraggable : $droppable, null, 'fast', dropSettings, null);