* Removes (partly) the ArchivingOrchestrator
* Removes the cli_feeder module, and makes it the 'default', allowing you to pass URLs directly on the command line, without having to use the cumbersome --cli_feeder.urls. Just do auto-archiver https://my.url.com
* More unit tests
* Improved error handling
* Keep twitter_api_archiver
* Remove unit tests for obsolete archivers
* Guess filename of media using the 'Content-Type' header
* Add mechanism to run 'expensive' tests last (see conftest.py) and also flag expensive tests to fail straight off (pytest.mark.incremental)