When passing a const message string to the error reporting APIs
RBD forgot to use "%s" to avoid GCC format string warnings
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

We used to prefix 'rbd:' to volume names, this is not necessary.

Qemu takes RBD devices in this way, like: qemu -drive rbd:pool/image

When attaching a network disk like RBD to a guest we however do not use this prefix.

Currently you can't map a RBD volume name directly to a domain without removing the prefix.
Signed-off-by: NWido den Hollander <wido@widodh.nl>

This patch adds support for a new storage backend with RBD support.

RBD is the RADOS Block Device and is part of the Ceph distributed storage
system.

It comes in two flavours: Qemu-RBD and Kernel RBD, this storage backend only
supports Qemu-RBD, thus limiting the use of this storage driver to Qemu only.

To function this backend relies on librbd and librados being present on the
local system.

The backend also supports Cephx authentication for safe authentication with
the Ceph cluster.

For storing credentials it uses the built-in secret mechanism of libvirt.
Signed-off-by: NWido den Hollander <wido@widodh.nl>