UserProvisionable now is a abstract table that belongs to the provisioning app. Also, items that are added there should not be deleted. A ModelManager is responsible in handling provisioning/deprovisioning, as well as showing what are the current items. Due to the big number of changes, a database migration reset is in order.

Signed-off-by: Raphael Lullis <raphael@lullis.net>
Merge branch 'master' of ssh://github.com/litedesk/litedesk-webserver-provision