Migrate promote.css to Stylus

Pretty self-explanatory, aside from the fonts.

I moved all fonts that are still needed by the Promote page from *media/fonts* to *media/redesign/fonts* and symlinked the former to the latter. This makes the fonts available in both the redesign and the old design, but also makes it easier for us to remove *media/fonts* after the redesign launches.

Anyway, GitHub shows the full addition/removal of *ABTSmilk.svg* because it's a plain-text file, so the diff is kind of ugly. Just remember that this all amounts to moving the fonts around.