Enable cumulative report from test set level

Enable fecthing cumulative report from test set level as well
(previously only product level was allowed).
Basic test for test set level cumulative report

Since the files uploaded are the same as in product levelt test case the
outcome is also same, but this verifies that the report can be received
at least.
Add /reports/:id/summary.json

Since there is a shortcout route for a report which can return json,
added also a route for fetching the summary.
Merge branch 'dev'