Reporting script can die on the orchestrator

[cle-ros]

When running on a cluster, clicking both the "download" buttons on the report site can lead to a crash of parts of the webapp.

steps to reproduce:

1. start flambe on cluster
2. wait until reporting becomes available
3. click on both "download" buttons
4. click on console. There, you'll see Oops! Results not available

[yukw777]

As @iitzco-asapp mentioned, this is b/c the simple flask server cannot handle parallel requests. We can solve this issue by running the report site behind a wsgi server such as gunicorn. More information here: https://flask.palletsprojects.com/en/1.1.x/deploying/wsgi-standalone/. I do fear running the report site behind a wsgi server may be an overkill though.