To check for migrations it needs to be able to read the lms.env.json and
lms.auth.json files for edxapp, and to be able to link services it needs
to be supervisor.

Jibsheet/xenial ansible2 mongod fixes

It won't find the old init script and use it the way Ansible1's
service.py did.

Add role for installing Docker tools

Add retry on ssh failure

remove ec2_ami_2_0_0_1 module so we begin using the one built in

This is purely for testing, as running docker inside docker
requires further shenanigans, but at least it'll catch if we
ever break this role.

Correct Package for libssl-dev

Update to ansible 2.x

These are the same versions as what the rest of configuration is currently set to.

Run pre-supervisor as www-data since supervisor doesn't really need access to the env and auth json.

Previous versions of ansible did not have the errorcatching capabilities to catch this.

So we can now log its output.