access processor allows unsafe query param keys

[clayg]

stats.access_processor.AccessLogProcessor.log_line_parser counts up the query params on a request as it goes along in order to track the number of requests that used format, path, delimiter, etc.

When a query param collides with an pertinent data key (i.e. method, code, year, etc.) it will over-write the matched value in the line_data dict (d) with a literal 1 circa stats.access_processor.py:98

One solution may be to whitelist the query params we want to count, so we don't accidentally break the expected format of the returned line_data structure.

[John Dickinson (notmyname)]

This description is a little off. The query parameters won't collide since the returned dictionary is built after the query parameters are handled.

Nonetheless, a whitelist of valid parameters is a good idea to prevent some future rearrangement of this code from causing this error to surface.