gitweb: Denote non-heads, non-remotes branches

Given two branches residing in refs/heads/master and refs/wip/feature
the list-of-branches view will present them in following way:
master
feature (wip)

When getting a snapshot of a 'feature' branch, the tarball is going to
have name like 'project-wip-feature-<short hash>.tgz'.

Signed-off-by: Krzesimir Nowak <redacted>
Signed-off-by: Junio C Hamano <redacted>