connect: accept file:// URL scheme

connect: accept file:// URL scheme

We might make it something like: "if you use an url, we don't default to
local", so the difference would be that

	git clone file:///directory/to/repo

would work the way it does now, but

	git clone /directory/to/repo

would default to "-l" behaviour. That kind of would make sense (and should
be easy to implement.

This adds support for "file://" URL to underlying connect
codepath to make it happen.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>