decode file:// and ssh:// URLs

decode file:// and ssh:// URLs

We generally treat these as equivalent to "/path/to/repo"
and "host:path_to_repo" respectively. However, they are URLs
and as such may be percent-encoded. The current code simply
uses them as-is without any decoding.

With this patch, we will now percent-decode any file:// or
ssh:// url (or ssh+git, git+ssh, etc) at the transport
layer. We continue to treat plain paths and "host:path"
syntax literally.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>