ssh: simplify the code

ssh: simplify the code

There's no point in shipping PATH to the remote server, since
it will be different there. We can also simplify the loopback
check, and we don't really need to munge the PATH there either
if we just use path.exe() in place of a plain 'bup' for it.

While at it, also fix the formatting instruction for the ints
to %d, instead of %s.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Rob Browning <rlb@defaultvalue.org>