Add my GNU email

Use getmail to fetch my GNU mail over pop3.

After stowing getmail config, run it like this the first time:
    getmail --store-password-in-gnome-keyring
to save the password in the Default gnome keyring.

Then, proceed to run it without arguments, and/or enable and start the systemd
timer for auto-syncing.

Requires:
    getmail
    gnome-keyring
    python2-gnome-keyring