Add testcase_stats role to publish testcase_stats HTML on openQA
    
    As with fedora_nightlies, I'm offloading this from my personal
    domain. Happily this one doesn't need a consumer, it just runs
    hourly. Again we just dump the output in openQA's public dir.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>