Any Python module in this directory with a name of the form:
    http_handler_XXX.py
is expected to have a handle() function which will be passed HTTP requests made
to the path /atropine/<tourneyname>/XXX/...

def handle(handler, tourney, remaining_path_components, query_string)
    handler: the Python HTTPRequestHandler, which contains details of the
    request. https://docs.python.org/3/library/http.server.html#http.server.BaseHTTPRequestHandler
    tourney: the countdowntourney object.
    remaining_path_components: the list of path components after XXX.
    query_string: the query string after the "?" in the URL, or the empty
    string if there is no query string.
