show version number somewhere on the web application

Created by: das-g

As a tech-savvy user, I'd like to know what version of Osmaxx is running on an installation I'm looking at over the web, so that I can

• include this information in bugs I report
• look up what known issues this version has (according to bugs reported by others)
• know what features I can expect (by comparing with milestones and releases on GitHub)

As a developer, I'd like to know what version of Osmaxx is running on an installation I'm looking at, so I can tell whether a scheduled deployment has actually been performed.

In either case, I want to be able to determine this version number without having to access the server backend (e.g. by SSH). Requiring accessing the web backend (/admin URL) is acceptable, but would be unfortunate. Optimal would be not even requiring to be logged in.