Show teams and members

[TheLastProject]

This is going to need some custom code using the https://developer.github.com/v3/orgs/teams/#list-teams and https://developer.github.com/v3/orgs/teams/#list-team-members API calls. Also need to make sure private users don't show up.

This is especially useful in relation to Pext/Pext#68, so that users can easily see all members in the moderator team.

[TheLastProject]

Preferably, we find an existing library for this, hopefully in PHP so it's easy to just run on the server without extra work. I'd rather not recreate and maintain this myself.