Fix bash completion to look in actual cow directories
    
    Fix bash completion to look in the actual cows/ directory.
    
    It appears that cowsay used to store its cows in
    /usr/share/cowsay and that is where the cowsay.bashcomp
    file also looked. However, cowsay now stores its cows in
    /usr/share/cowsay/cows, so the bash completion should look
    there as well.
    
    Note that the bash completion should also look into
    /usr/share/cowsay/site-cows/ and wherever else cowsay
    looks for cows.