Add multiple sites per instance on different domains

[mrchrisadams]

Use the django sites framework to allow the creation of new 'constellations' at different domains.

Because already have profiles separated from users, we'd scope our search queries to a given site, but allow a user to see the different constellations they were signed into, using the same email address or credentials.

[mrchrisadams]

I've had a bit more of a think about this.

While this would be cool, it's an open question as to whether making the changes at the application level make more sense than just having separately deployable django instances.

The django sites framework was created when setting up and running a django app was a fairly heavy weight proposition, and it's getting easier to create deployable applications that scale up and down with traffic.

Rather than having one server with one django instance with multiple constellations, it might make more sense to assume someone would deploy multiple django instances, each running a single constellation, run on some kind of virtualisation like a container, MicroVM, or so on.

This way, the isolation between constellations is achieved by having a bit of config per applicatiion, rather than us writing lots of multi-tenant code to make sure queries are always scoped appropriately.