Add a slot page `/<flavour>/<slot>/` and fix a couple of unhandled 404 errors
- report as 404 when requested a slot build not in the database
- report as 404 when test result zip file is missing
- show the list of most recent builds for a slot via the view
/<flavour>/<slot>/
(similar to the releases report)
Closes #53 (closed)
Edited by Marco Clemencic