core: host stuck on Unassigned when moving from status Maintenance

This patch makes sure the move of the host from Up to NonOperational
is logged in the Audit Log

Change-Id: Ib88fcd733ec0b72fca7d8e6d40c4d28a7d926333
Bug-Url: https://bugzilla.redhat.com/962180
Signed-off-by: lzelkha@redhat.com <lzelkha@redhat.com>