Add team discussions view

[andrewda]

What Currently Happens?

No way to see Team Discussions.

What Would You Like To Happen?

I'd like to see Team Discussions be implemented into the app. It's not going to happen yet, because the Team Discussions API hasn't yet been released, but when it is, this would be great addition.

[machour]

For people wondering what are team discussions: https://github.com/blog/2471-introducing-team-discussions