Make munge integration tests more end-to-end

Ensure that the munge integration tests go through as much of the
pipeline as possible, including through @psd's fetching process. The
only part of the pipeline we don't touch is the curling of the correct
files down to the cache folder.

This has involved adding a bunch of command line options to `generate-redirects.sh` allowing us to change paths, which are currently only used in the tests.