Our blog should live at DOMAIN/blog not DOMAIN/category/blog

I want this change mostly for minor aesthetic reasons. But I think the existence of the "blog" category is a clear sign that whoever first set the site up didn't understand Jekyll collections to (1) exist, and (2) be great. Both 1 and 2 are true of me, so I'd like a more-reasonable setup for the blog and any other content-types we're looking have later.