The function is named ListMetadata but returns a map of all
the metadata assigned to the rbd image. It is named ListMetadata to
match the C librbd api call.
Signed-off-by: John Mulligan <jmulligan@redhat.com>
As rbd.go is very long, and the get-/set-/remove- metadata functions in
rbd.go make a nice logical unit, move them to a new metadata.go file.
Signed-off-by: John Mulligan <jmulligan@redhat.com>