vivi: Launch MariaDB 10 with spiped

Summary:
This adds the basic infrastructure to vivi for mysql01 - in particular, it just adds the newest MariaDB 10 package along with an spiped frontend controlled by systemd. There are maybe some tweaks we could make to the configuration, but this works just fine right now.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

Test Plan:
Run 'nixops deploy --include mysql01' and watch it work. Jump in via SSH and run 'systemctl start spiped@mysql' to start the spiped frontend service.

Reviewers: relrod

Differential Revision: https://phabricator.haskell.org/D6