rewritten with mongojs

thud.js entirely removed
further cleanup to reduce callback hell
further code tidying up
move logic returns tween instead of executes it

centralized tween execution to apply_ply
removed some unused files
rewrote callbacks again

cpu validates captures on all moves, t or d.
fixed issue: vacated capture square not cleared

standardized all "game" variables to "game_id" where applicable in IO
moved deletion to appropriate end event
Merge pull request #4 from hexparrot/mongod

Mongod