Instead of using one Git repository per package, use a single large
object storage for space efficiency. The refs of the individual package
bases are divided using gitnamespaces(7) which allows for exposing each
namespace as an independent repository easily. Also, git-serve is
modified to create a branch for each package, allowing to browse the
large repository with cgit.

Helped-by: Florian Pritz <bluewind@xinu.at>
Helped-by: Johannes Löthberg <johannes@kyriasis.com>
Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>