Browser-based integration tests #1466

Currently, our test coverage for CWS/AWS is quite poor. I think the only reasonable way to test them is to load them in a browser and verify that all pages behave correctly. This can be automated using something like selenium.

I think I would want it to be something like the current functional test suite, i.e. that it's one long-running test that starts by creating the necessary database objects and then performing a bunch of actions on them. I think it'd be good to have this running inside pytest, to avoid having yet another thing we need to run separately, but I'm not sure how to set that up...