rsync transport: allow local paths, and fix tests

rsync transport: allow local paths, and fix tests

Earlier, the rsync tests were disabled by default, as they needed a
running rsyncd daemon.  This was only due to the limitation that our
rsync transport only allowed full URLs of the form

	rsync://<host>/<path>

Relaxing the URLs to allow

	rsync:<path>

permitted the change in the tests to run whenever rsync is available,
without requiring a fully configured and running rsyncd.

While at it, the tests were fixed so that they run in directories with a
space in their name.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>