Always choose highest requested debug level
    
    Allowing the CLI to lower the debug level specified in a config file
    is dubious, and previously broken since we don't distinguish "default
    value" from "explicitly requested value of 0" in popt.  This resulted
    in "Debug Enabled (level: 0)" even when the log level was not actually
    0, which is confusing for users.
    
    Remove the gp_debug_args() function since it is no longer used.
    
    Signed-off-by: Robbie Harwood <rharwood@redhat.com>
    Reviewed-by: Simo Sorce <simo@redhat.com>
    Merges: #229