Group-level issue boards: make the project of an issue visible

Consider this screenshot: https://gitlab.com/groups/gitlab-org/boards/364268?milestone_title=10.1&scope=all&utf8=%E2%9C%93&state=opened&label_name[]=Geo

Screenshot_from_2017-09-25_16-22-20

There are two postgres_fdw issues - one for support in gitlab-ee, one for support in omnibus-gitlab.

It's impossible to tell which is which from the view, though. You have to mouseover and inspect the issue URL to find out which one is which.

Let's add the project name, qualified by subgroups of the group you're viewing the issue board from.