[RFC] Remove @owner and @user from package list

[Garrett Cooper]

Hi again arch,
    When doing some research, it appears that while functionality in
theory exists for @owner and @user in the package list, it isn't
actually used in the pkg_install code at all, adding unnecessary bloat
to package lists;
    FWIW this functionality (just like @exec and @unexec) can be
implemented via pkg-install or more reliably via an mtree file.
    Thoughts?
Thanks,
-Garrett