Improve configurability of consumers and CLI, add tests
    
    Summary:
    This is mainly about making the fedmsg consumers configurable.
    We also do a bunch of cleaning up in the config settings and
    offer more settings in the CLI as well.
    
    I took the opportunity to rework the consumer class naming to
    be more consistent; note this will break existing consumer
    configs, they will need to be updated. I will update the infra
    deployments.
    
    We also add, well, tests. Lots of tests! All the consumers and
    the entire results module are tested, which should help us be
    confident these changes are OK. I didn't have enough time to
    write tests for schedule or cli yet, will do it ASAP.
    
    There's a little bit of general cleanup too - unused imports and
    so on.
    
    Test Plan:
    Run the tests! There are tests now. Also actually use
    the CLI and ideally the consumers and make sure they really do
    work, and my tests aren't lies.
    
    Reviewers: jskladan, jsedlak
    
    Reviewed By: jsedlak
    
    Subscribers: tflink
    
    Differential Revision: https://phab.qa.fedoraproject.org/D1118