Add option '--copies' to 'cluster snapshot load'

[sirio81]

First this but has to be fixed: 1272305.
This will make 'cluster snapshot load' to format the cluster with the same redundance scheme as it was saved.

Rational:

in case of disaster recovery or to restore a cluster snapshot on a separate testing cluster, it may be necessary to set a different redundance scheme.

E.g.

production cluster running with --copies 8:4.
I need to restore it's snapshot on a testing cluster with few (or even one) node.
Another case is that the production cluster it self got 5 or more servers damages.
In this example, I couldn't restore on a cluster with less than 8 nodes.
In any case, I think it's a good thing to be able to choose the number of copies when restoring a 'cluster snapshot'.

New syntax:
dog cluster snapshot {save|list|load} [-a address] [-c copies] [-p port] [-h] <tag|idx> <path>

[sirio81 (sirio81)]

Is the fix committed in master or devel branch?

Note:
I don't see the new option in the help message

Sheepdog daemon version 0.8.0_101_gbf21156

dog cluster snapshot load --help
Usage: dog cluster snapshot {save|list|load} [-a address] [-p port] [-h] <tag|idx> <path>
Available subcommands:
  save save snapshot to localpath
  list list snapshot of localpath
  load load snapshot from localpath
Options:
  -a, --address specify the daemon address (default: localhost)
  -p, --port specify the daemon port
  -h, --help display this help and exit