The volume sources for an OSD on PVC were relying on the ordering
of the volume sources slice. While this was working, it was causing
headaches and potential future developer error when being
interpreted incorrectly. The addition of the wal pvc device
would make the issue even more pronounced. Now each PVC used
for the OSD will be identified in a map by name such as data
and metadata.
Signed-off-by: Travis Nielsen <tnielsen@redhat.com>