Directory-based OSDs are failing to deploy because 'python' has
been replaced with 'python3' in the image. This change updates the
python commands to use python3 instead.
There is also a dependency on forego, which has been removed from
the image. This change also modifies the deployment so that it
doesn't depend on forego.
Ownership of the OSD keyring file has also been changed so that it
is owned by the 'ceph' user, and the ceph-osd process now uses
--setuser and --setgroup to run as the same user.
Change-Id: If825df283bca0b9f54406084ac4b8f958a69eab7
131ea21512