Change name of bash completion file to just "cowsay"
Change the name of the installed bash completion file from
"cowsay.bashcomp" to "cowsay".
Of the 1000+ files in /usr/share/bash-completion/completions/ on my
system, no other file is called "*.bashcomp". Most are just called
the same as their respective command.
We also let the filesystem package take care of owning the
directory /usr/share/bash-completion/ and its subdirectories.