put() and get(): use random temp file when use_sudo=True
put() and get(): use random temp file when use_sudo=True

This was using a hash of the host and remote file path,
and could result in an unnecessary failure if there were
multiple simultaneous get() and/or put() of the same file
path on the same host.

cmattoon/fabric,ploxiln/fabric,mathiasertl/fabric