packaging: do not package libdir/ceph recursively

Package libdir/ceph non-recursively, to avoid duplicates, and
package libdir/ceph/ceph_common.sh explicitly.

Signed-off-by: Alexandre Oliva <oliva@gnu.org>
Signed-off-by: Ken Dreyer <ken.dreyer@inktank.com>
Merge pull request #1224 from kdreyer-inktank/packaging-libdir

packaging: do not package libdir/ceph recursively