Setup subdomain (i.e. aktivitet.team13.se) and use for main and test sites

[marcus-sonestedt]

The users should see a familiar domain name, not @marcusl 's account name and the webhost provider.

TODO

• [ ] Create subdomain redirecting to webapp-2275.eu.pythonanywhere.com
• [ ] Configure eu.pythonanywhere.com to accept that subdomain on the current site
• [ ] Update all links in emails, sms:es, etc (move to settings.py or detect somehow)

Describe alternatives you've considered Keep running as is, will confuse people, but it works so this is not critical.

Additional context https://aktivitet.team13.se seems workable.

[marcus-sonestedt]

Moving to backlog while we wait for our main website host to set up subdomains. (Not likely to happen this year, by the looks of things...)