In the server add backup target host for scp

[TAlonglong]

Feature Request

Add backup or aditional target hosts using scp in server.

Some pseudo code suggested by @pnuu

if transfer_failed and "backup_target" in config:
    for tgt in config["backup_target"]:
        status = retry_transfer(msg, target=tgt)
        if status:
            break

This will allow more than target hosts when using scp with the server which will increase redundancy I need for my setup.

Assign this to me and tag it for PCW