v2.0
Merge branch 'master' of https://github.com/JimLiu/angular-ui-tree

Conflicts:
	README.md
	demo/demo.js
	demo/dist/angular-nested-sortable.js
	demo/dist/angular-nested-sortable.min.js
	dist/angular-nested-sortable.js
	dist/angular-nested-sortable.min.js
	source/helper.js
	source/nestedSortableCtrl.js
	source/nestedSortableItemCtrl.js
	source/uiNestedSortableHandle.js