Support multiple subdomains when creating a new media

This works for me. It's either a change to a * or + depending on if a subdomain is actually required, and I truly don't know that.

dave reid → changed the visibility of the branch 3507596-fix-regex to hidden.

Dave has a good point, but I wasn't willing to make a change I wasn't sure was right. I don't understand the need for the complexity so I end up leaving it.

Automatically closed - issue fixed for 2 weeks with no activity.