gitweb: Show project's git URL on summary page

gitweb: Show project's git URL on summary page

Add support for showing multiple clone/fetch git URLs for project on
a summary page. URL for project is created from base URL and project
name.

For example for XMMS2 project (xmms.se) the git base URL would be
git://git.xmms.se/xmms2.

With corrections from David Rientjes <redacted>

Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: David Rientjes <redacted>
Signed-off-by: Junio C Hamano <redacted>