Update Copyright header point to COPYING file
    
    Point to a file containing the license rather than including
    it in every single source file. This will make it easier to
    manage the license in the future without another humongous
    commit.
    
    https://fedorahosted.org/ipsilon/ticket/126
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>