Class Twitter widget on class homepage

Twitter widget for class home pages. (#2247)

Widget depends on new database field (thus this PR requires a migration) which, if not present, prevents this widget from loading. This widget is a search widget so any search term or tag works (i.e. #dbclass, @dbclass, dbclass, etc...). This widget has no profanity filter but does play well with python/django integration and custom styling. Also has different settings (i.e. loop, live, timing, avatar display, etc...).