Use standard logging facilities
    
    This patch adds support for logging messages from the autoqa script and
    watchers. There are two new cmd line options controlling what's
    printed out on stdout: --debug (print everything) and --quiet (print only error
    messages). --verbose option was removed and is now default one.
    Everything is logged into the log file (specified in autoqa.conf) except
    debug messages. Logging debug messages into the log file can be turned
    on by setting debug option in autoqa.conf.
    
    Fixes: #196