[impdev] Imprudence 1.3.1 finalized

[Jacek Antonelli]

I've pushed to the 1.3-maint branch. Armin and McCabe, please check
that it still works fine for you. If there aren't any last-minute
issues, I'd like to release it today (Feb 24).

  https://github.com/imprudence/imprudence/commits/1.3-maint

(Note: the "news bar" on the login screen is expected to currently
show a black web page with a tiny Imprudence logo in the bottom right
corner. Later we'll write some PHP magic to have links to the latest
blog posts.)

- Jacek