Move the logic from different places in the view code, and also start
supporting linking to guix.cbaines.net builds. I'm unsure quite how to
generalise this, but just starting doing it is probably the way forward.
Previously, a connection was passed through the code handling the
request. When queries were performed, this could block the thread though,
potentially leaving the server unable to serve other requests.
Instead, this now runs queries in a pool of threads. This should remove the
possibility of blocking the threads used by the web server, and in doing so,
some of the queries have been parallelised.
I''m still not sure about the naming and syntax, but I think the functionality
is a sort of step forward.
