Simplify the devel/upload script

Instead of multiple uploads to each node, this script copies everything
as needed to the temporary directory, exactly as to be installed in the
destination machine, then runs only one rsync per host.

This is more dangerous (we can break /etc now), but for development
machines is fine.

The patch then also uploads the bash completions and the current name
for the cron job (I think that ganeti-master-cron is a deprecated name,
not that someone actually intends to upload a file named like that). A
flag --no-cron is added to skip uploading the cron file if desired.

The patch also changes rsync to propagate the file permissions.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>