* fixed race condition in channel being closed before all messages have had a chance to be pushed through

* re-refactored stackable trait pattern due to bugs in calling super method chains

* tidy up crawler exceptions to use sealed ADT
Fixed a bug  where redirected relative Location header URIs were not handled (example -- Location: /ui/)
fixed a nasty bug where throttlerspec would take down the test server
Clean up link scraper code, and fix improper ordering of future code
add scct code coverage
catch 404s and bad requests and respond with text instead of html
fix wrong status