bashrc & zshrc: enable apt process bar.

If we are as root, mkdir -p /etc/apt/apt.conf.d and run the command
echo 'Dpkg::Progress-Fancy "1";' > /etc/apt/apt.conf.d/99progressbar .

This is untested and I am unsure what does OS X think about this, but I
don't have OS X anywhere, so I might not care about it so much.