Bringing code up to speed with WordPress.org
Adding subscribe or update method to the mailchimp API
Switching to list add or update method
Hardcoding group interest subscriptions
Removed hardcoded restriction on group interets
Some bug fixes for the dynamic group subscriptions
Subscription preferences are working
Adding already subscribed message option
Fixing bug with subscription conditional
Improving plugin arch: using uninstall.php, removing autoloader
Removing the donate code
Some code cleanup to make the widget a bit more readable
Pulling out the widget generation into a template for theme override

Inspired by @beingtree
More code cleanup
Bootstrap 3 form template formatting