The directory nesting is unnecessary here and confusing to navigate. I've moved
all apps to the project subdirectory, currently called "www", but soon to be
renamed "conservancy".
I've also moved manage.py to the top-level directory.
First and foremost, the mime type has to be supported by the web
server. Either you have to add a `.vtt` mimetype, *or* just put it
as a `.txt` file. I chose the latter since it doesn't require a
custom Apache configuration.
Second, even if you make it a `.txt` file, using a CDN does not seem
to work. I suspect that maybe CDNs do really weird things with
mimetypes when they server them, or maybe the <track> element just
really doesn't like it when the URL is 301'd. 🤷
Anyway, with these two changes: using a `.txt` file, and hosting the
file locally, the subtitles now work properly!
Note, if you use the `default` attribute in the <track> tag, it'll
turn them on by default. Leaving it off does allow the user to turn
them on in my tests in both Chromium and Firefox.
