List some non-visible teams in the team listing (#1158)

If a team has their membership policy as either open or
application-only, then we should list them in the team listing.  This
allows users to have a simple way to join the team.

Changed the help text for is_visible to reflect the new meaning of the
column.
Updated team views for new listing system (#1158)

Made the dashboard view visible to non-members for teams that are
private, but accept applications.  Changed what we put in the
dashboard page in this case.
Merge branch 'staging' into gh-1158
Fix redirect after approving an application (#1158)
Don't show metrics links if they will result in a 404 (#1158)
Merge pull request #1175 from pculture/gh-1158

Gh 1158