Added maintenance mode on restarts by default. During a manual restart or during an autorestart (ie: check-http),
it will create the maintenance file to prevent any other autorestart during the time specified in MAINTENANCE_TIME variable.
Maintenance file is now being deleted only if it was not present before. Otherwise, we basically do nothing.
Add a maintenance mode callable from xwiki.sh. It can be turned [on] and [off] as an argument, but if no one is provided,
it will switch to the opposite mode than the current state. It's still done with the presence of a maintenance file in $CONF_DIR.
Switched to recursive maintenance function to avoid code duplication
Release of Xinit 1.2.3, update of release notes.
Merge branch 'prevent-restart-loop' of https://github.com/xwiki-contrib/xinit into prevent-restart-loop
Merge pull request #9 from xwiki-contrib/prevent-restart-loop

Release of Xinit 1.2.3