The new parameter --review-mode allows to specify how the review bot should handle obs reviews
normal: accept review if check is good, decline if bad
no: don't accept or decline requests
accept: always accept review, even if check fails
fallback-onfail: accept review and set other user or group as review if check fails
fallback-always: always accept review and set other user or group as reviewer afterwards
if a review for the maintbot user is added for a second time the old
function would only see the 'accepted' state of the first review and
the bot would not change the review state.
factory-source checks if submissions contain sources already accepted in
Factory. maintbot makes sure maintenance submissions are authored by the
Factory package maintainer.
Both are based on a new generic ReviewBot.py class that can serve as
common framework for review bots.
