Include theme and version in page HTML

[StephDriver]

User story

When I spot a bug in the middle of another task, I want to be able to record it quickly as an issue, without diverting from that task. Especially as a newer member of staff, I don't have all the journals in my head yet, so I have to log in and find out, or guess. Having spotted a bug, I've likely pulled up the inspector already, so if the theme and version number were included in the HTML, that information would already be to hand.