Limit jobs shown by site

This doesn't handle a ton of edge cases and allows for filtering on the current site only. It will break My.jobs postajob pretty much entirely at this point, which I'm trying to find a way around. I'm also trying to think up all the edge cases. At a little over 900 lines, it's time for someone to at least start reviewing it, though.

All tests pass.
It's using the host middleware, which is what sets the site information by domain name.  So conjunction, if I understand your question correctly.