This creates a module for the draggable pointers for the RevisionSlider
mainly to encapsulate both the pointers' state and their HTML code.
Some animation methods such as slideToSide and slideToPosition
that are still flying around in init.js weren't added to the
module since I thought they should be part of the not yet existing
Slider module.
Change-Id: I1292bfb0bbd68f8d2de04b3b5e5f3133ec6363b8
