[schema,server] add a security debugging aid (closes #2920304) - Add a DGB_SEC debugging flag (to be used with set_debug/debugged). - Add a context manager (tunesecurity) to filter security assertions. Note: this does not address all read-security mecanisms.

usr/lib/python2.4/site-packages/cubicweb/
etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances