When I originally deployed Ubuntu 16.04 there were no public xenial
MariaDB builds yet, so I used wily (15.10). Now there are official
xenial builds so we can use them instead.
When you use the apt_repository module it adds a sources.list with
an annoying filename, and also it's just easier to use a template
when we have different distros/versions to support.
Ansible's mysql module can get this password and connect fine, but
`mysql` on the command line chokes if the password is slightly
complicated and is not quoted.
Signed-off-by: Alan Orth <alan.orth@gmail.com>