WIP: hacking around trying to find a neat approach
first working impl of default filenames for exports. had to add endpoints to get metadata for exports before actually running them because the streaming api didn't permit getting to the headers before diving into the stream
escape spaces in filenames and include authority_id in filenames for agents when present
added a test for the EAD export metadata endpoint
removed some debugging cruft
cleaned up some unused changes
Merge pull request #594 from hudmol/default-filename-for-exports

Default filename for exports