Standardises on testing URL

For development purposes, the specs assume an API is available at
http://api.brightbox.dev

This can be setup to point at any backend dev server on any host or port
but that is left as an exercise to the reader.
Removes filtering and rerecords

The filtering was not working very well, changing the Authorization
headers a bit too much.

Since all the recordings are now using sample configs with a sample user
for development (and not leaking real details) the filtering is not as
important.