Remove highlighted_qs from teams list

We aren't using it anymore.
Better way to query counts for teams list

Use subselects instead of annotate (which uses group by) to count
members.  This runs much faster.

Use a similar query to count videos, which avoids an extra query for
each team on the list.

Renamed member_count() to members_count().  I think it's nicer for the
name to have the same form as videos_count().
Avoid extra queries to check team membership for the teams index

Before we using an extra query for each team on the page.  Changed it
so we query team membership when we fetch the teams.
Merge pull request #1800 from pculture/speedup-teams-list

Speedup teams list