http-push: support full URI in handle_remote_ls_ctx()

http-push: support full URI in handle_remote_ls_ctx()

The program calls remote_ls() to get list of files from the server over
HTTP; handle_remote_ls_ctx() is used to parse its response to populate
"struct remote_ls_ctx" that is returned from remote_ls().

The handle_remote_ls_ctx() function assumed that the server returns a
local path in href field, but RFC 4918 (14.7) demand of support full URI
(e.g. "http://localhost:8080/repo.git").

This resulted in push failure (e.g. git-http-push issues a PROPFIND
request to "/repo.git/alhost:8080/repo.git/refs/" to the server).

Signed-off-by: Kirill A. Korinskiy <catap@catap.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>