WIP: SlapObject: when destroying a partition, no residues from user activity should remain
When users connect to a slappart by ssh, they can run or plan tasks running in the background. As these aren't run by supervisord, they are not stopped when the slappart is destroyed, and they remain even when the slappart is attributed to another user.
In the consequence of this, instanciation errors can appear later if the services run in background are using some ports that the new user wants also to use, or even worst.
This patch proposes to kill all the processes belonging to the slapuser when its slappart is destroyed, and clean the user's crontabs and at jobs.