Add info about Stylus to the setup docs.
Use an empty alt attribute in image banners.
Fix DeprecationWarnings from non-aware datetimes.
Make customization dropdown labels consistent.
Use &times; to separate dimensions for image size.
Update milestone strings to latest copy and mark them for l10n.
Remove resolved TODOs.
Make links in banner code absolute so they work on other sites.
Replace strings.py with template+view and remove <span> from categories.

Template + view will allow localizers to edit the strings via pontoon.