With the current code, the images from picon and gravatar are
requested over http://, and browsers give mixed contents warning
when gitweb is served over https://.
Just drop the scheme: part from the URL, so that these external
sites are accessed over https:// in such a case.
Signed-off-by: Andrej E Baranov <admin@andrej-andb.ru> Signed-off-by: Junio C Hamano <gitster@pobox.com>