Temporarily bypass medic-api for some special CouchDB URLs.

Toward https://github.com/medic/medic-webapp/issues/631. We need to
figure out what the underlying issue is in medic-api, but this should
buy us some time until we can do that. I've chosen to skip a few of the
special handlers like /_restart, /_active_tasks, and /_uuids for now.