Do not make directories by mistake.

Rational: I found I had created a series of OSD directories under "/dev/" when disks I thought existed did not exist.
Warning: This change will be noticed by end users and may effect deployment infrastructures.

Note: Please note this patch resolves this issue for ceph-deploy.
https://github.com/ceph/ceph-deploy/pull/224
Signed-off-by: Owen Synge <osynge@suse.com>
Merge branch 'wip-dont-mkdir-by-mistake' of github.com:osynge/ceph into wip-dont-mkdir-by-mistake