OO-798, OO-797, OO-796: update the webdav implementation based on Tomcat, make OpenOLAt work under root context, small refactoring of the dispatchers, push raw files dispatcher to its own servlet, implements Digest authentication...

OO-271: refactor the user session management, move the the logic in its own manager, persist the time out values, make the admin GUI a bit better

--HG--
branch : bps