Allow a custom setState handler on the using component

Only components having a state are currently working correctly with the sortable mixing. The proposed fix is to allow custom state handling method to be passed in as config.

react-sortable-mixin.js

@@ -81,7 +81,7 @@
 
 
         componentDidMount: function () {
-			var options = _extend(_extend({}, _defaultOptions), this.sortableOptions || {}),
+            var DOMNode, options = _extend(_extend({}, _defaultOptions), this.sortableOptions || {}),
                 copyOptions = _extend({}, options),
 
                 emitEvent = function (/** string */type, /** Event */evt) {
@@ -120,7 +120,11 @@
                         }
 
                         newState[_getModelName(this)] = items;
+                        if (copyOptions["stateHandler"]) {
+                            this[copyOptions["stateHandler"]](newState);
+                        } else {
                             this.setState(newState);
+                        }
                         (this !== _activeComponent) && _activeComponent.setState(remoteState);
                     }
 
@@ -130,9 +134,10 @@
                 }.bind(this);
             }, this);
 
+            DOMNode = this.getDOMNode() ? (this.refs[options.ref] || this).getDOMNode() : this.refs[options.ref] || this;
 
             /** @namespace this.refs — http://facebook.github.io/react/docs/more-about-refs.html */
-			this._sortableInstance = Sortable.create((this.refs[options.ref] || this).getDOMNode(), copyOptions);
+            this._sortableInstance = Sortable.create(DOMNode, copyOptions);
         },
 
         componentWillReceiveProps: function (nextProps) {