rpm: implement scriptlets for the post-split daemon packages

rpm: implement scriptlets for the post-split daemon packages

This patch gives each of the ceph-{mds,mon,osd,radosgw} packages its own
%post, %preun, and %postun scriptlets dealing with the package's unit files.

The scriptlets of ceph-base are adapted to handle the ceph.target unit file
only.

The scriptlets of ceph-mon handle ceph-create-keys services in addition to ceph-mon.

The scriptlets of ceph-osd handle ceph-disk services in addition to ceph-osd.

Fixes: http://tracker.ceph.com/issues/14941
Signed-off-by: Nathan Cutler <ncutler@suse.com>
Signed-off-by: Boris Ranto <branto@redhat.com>