Support tornado>=6.0

[wallacbe]

Support tornado>=6.0

[dbhatman]

FYI #934 includes some failure example logs

[glados-verma]

When trying to run the dashboard_server with Python3.10, I see this error: AttributeError: module 'collections' has no attribute 'MutableMapping'. The current version of Tornado therefore caps us to using Python3.9 at the latest.

[matt-donahoe-skydio]

I added explicit asyncio event loops in the run() method of any threading.Thread subclass, like WebGuiServer and StationWatcher.

asyncio.set_event_loop(asyncio.new_event_loop())

I also had to delay the call to self.server.add_sockets(sockets) until the event loop was set for the thread, otherwise tornado would grab a reference to the eventloop of the main thread and get blocked, never responding to requests.

Seems to work so far, but I'm very new to OpenHTF, so I doubt I caught everything. I'll post a PR in a few days if no one beats me to it.

Here's my diff
matt-donahoe-skydio@fadbee1