Rewrite on top of React DnD

[samvtran]

This will also take care of the upcoming changes in 0.14 deprecating cloneWithProps so nothing needs to be done there.

• [ ] Update dependencies (#5)
• [ ] Redux-like API options (i.e., mixin, function, and decorator) (#6)
• [ ] Multiple targets (#12)
• [ ] Update to React 0.14 (#7)
• [ ] Touch interface via https://github.com/yahoo/react-dnd-touch-backend (#8)
• [ ] New docs (#9)
• [ ] New examples (#10)
• [ ] Tests (#11)
• [ ] Support nesting

Sortable props to port over:

• [ ] horizontal (probably as a string field for specifying grid as well or as a separate HOC)
• [ ] onSort
• [ ] minDragDistance

SortableItemMixin props to port over:

• [ ] isDraggable (A wrapper around canDrag)
• [ ] sortData