added first chessboard!

account.scala.html
- added js to show board with spare pieces (following chessboardjs example)

accountLayout.scala.html
- modified all links and scripts to use url instead of routes.App. format
- added base href for easy linking to js, images

chessboard-0.3.0.js
- changed patch of chesspieces from img/ to images/
- this change is not present in the min filet yet!