Move setting session.mtime from dbapi to web session manager
clean_session was broken since the switch away from dbapi on the web
side, since session.mtime wasn't being set anywhere.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html