Feature release 1.3.0

• New callbacks: dnd-dragend, dnd-canceled and dnd-inserted.
• Custom placeholder elements: dnd-list elements can have custom elements by creating a child element with dnd-placeholder class. This is useful for cases where a simple li element is not sufficient.
• dnd-nodrag directive: This directive can be used inside dnd-draggable to prevent dragging certain areas. This is useful for input elements inside the draggable or creating handle elements.
• Fix user selection inside dnd-draggable: The selectstart event is no longer cancelled.
• Fix click handler compatibility: Propagation of click events is now only stopped if the dnd-selected attribute is present.
• Fix IE9 glitch: Double clicks in IE9 previously would trigger the dnd-moved callback, and therefore remove items accidentially. (issue #21)