Roles page audit (or at least I tried)

[Pey Lian Lim]

I have started to audit our Roles page. See https://github.com/astropy/astropy.github.com/issues/519 . This will be a long process and perhaps some parts might even be controversial. Gotta start somewhere, right?

I will send out a separate memo for specific PRs tied to this effort. FYI.