Permanent URLs

[alexbainter]

Closes #175.

Adds Permanent URLs.

Overview

• Adds the PermanentURL model with fields for url (which stores the full URL) and for linking to either a Schema or a SchemaRef using Django's contenttypes framework.
• Adds a PERMANENT_URL_HOST setting (so we can use id.schemas.pub in production without completely* breaking other environments.
  • Permanent URLs are always stored without their port number and with https, so they don't quite work right out of the box locally (that is, the full url stored in the local database doesn't quite work as-is, but you can just change it to http and add the port number to get it to resolve locally)
• Adds a view to catch paths like /o/anything, redirect them to the appropriate object if a matching PermanentURL exists, or 404 otherwise
• Adds a form for viewing and adding permanent URLs for a schema/schemaref, accessible from the profile page for public schemas only.
• Updates the schema and schema ref detail pages to show permanent URLs

Assumptions/limitations/future work

• For now, only users in an organization can create permanent URLs for their schemas.
• All permanent URLs will be stored with "https", but the server will actually match https or http.

Profile page showing links to permanent URL management form

Permanent URL management form with no existing links

Permanent URL management form with existing links

Permanent links displayed on detail page

[lisad]

Was this index intentional ? If we do want it to make URL lookups fast, wouldn't it be to the URL instead of the object ID?

Together with the unusual dependencies, not just 'core' in the dependencies list above, I wonder if this is necessary?

[lisad]

NM I get it, because it's using the generic foreign key