init-ceph: clean up temp ceph.conf filename on exit

Signed-off-by: Sage Weil <sage@inktank.com>
common/MemoryModel: remove logging to /tmp/memlog

This was a hack for dev purposes ages ago; remove it.  The predictable
filename is a security issue.

Signed-off-by: Sage Weil <sage@inktank.com>
Reported-by: Michael Scherer <misc@zarb.org>