[wpmudev plugin , hub] Handle domain changes, www vs non-www, https vs http better

When a domain is configured to force SSL, wpmu tools consider that redirect to be a "down" state.

When allowing both www and non-www URLs, the Hub will show registrations for both.

When moving a dev site into production, registration needs to be repeated.

This could be streamlined to understand that these are typical steps in a site lifecycle.