Active ballots page, UI adjustments and security

Because the insanity-uploader tracks mailing lists for ballot announcements and stores them as events in the timelines of projects, it's possible to present a list of ballots active at the current time, which is a common requirement for users. Previously, this had to be done manually. The active ballots are listed on the home page, and a JSON version is available as /active-ballots.json; it is formatted as a Tablepress table so that it can be imported directly into Wordpress via its URL.

This release also contains bugfixes and security fixes.