Include coordinated and infrastructure package contributors in team page (was affiliated)

This page should include a list of affiliated package contributors (we need to decide whether to duplicate names already in the list of core contributors):

http://www.astropy.org/about.html

Start with the About page at http://www.astropy.org/about.html and determine where affiliated package contributors are maintained. Resolve whether names already listed as core contributors should be duplicated, then update the team page so the agreed contributor list is present.

Written by the indexing model from the issue text.