Zope CMF BitTorrent Tracker Code

* use a before traverse hook to disable CookieCrumbler
* stores torrents path in the dict, not torrent directly

define a custom permission

rename portal_tracker as portal_bttracker, use constants for Permissions instead of strings, implements a bit of authentication

remove unused workflow methods; store username, not user object

clean up the code

remove tabs

Improve codestyle (thx to pylint)
Initial work on http authentication for clients (not functional yet)

improve skins

add TODO list

cleaned up imports