ceph.spec.in:  Additional clean-up on package removal

When removing the last instance of ceph, also remove the files
created by ceph during operation.  These consist of the files
under /var/lib/ceph, /etc/ceph, and /var/log/ceph. Bug #4415.

Signed-off-by: Gary Lowell  <gary.lowell@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>