Prior to this change, ceph-base required the "parted" package, which
meant that any installation of ceph-osd, ceph-mon, or ceph-mds would
pull in the parted package.
Move the parted dependency to ceph-osd, since ceph-disk is the only
thing that uses parted.
The advantage of this change is that Mon and MDS systems will not need
to install the parted package.
Fixes: http://tracker.ceph.com/issues/16095
Signed-off-by: Ken Dreyer <kdreyer@redhat.com>