HTTP Stream live logs to admin

[trickeydan]

This is useful for during events, so that we can view the live logs, probably using a HTTP Stream.

Some useful stuff for doing this in Flask here: https://mortoray.com/2014/03/04/http-streaming-of-command-output-in-python-flask/

A SR thing that uses an HTTP Stream as an example: https://github.com/srobo/srcomp-stream