Piece 'type' -> 'name', add Raphael library, proper piece rendering

* Rename piece model 'type' to 'name' to fix conflict with Backbone
* Render pieces in SVG using Raphael.js, including piece 'angles'
* The piece 'facing' direction and allowed movements were conflicting
  thanks to negative rotation values; this has been fixed.
* Add 'temporary' rotation to pieces to allow rendering of current
  position before finalizing a move.