Integrate REX-Ray to manage persistent storage easily

[thomvaill]

Describe the solution you'd like
Persistent storage is a hassle with Docker Swarm, and is not covered at all in this project for now.
I propose to integrate REX-Ray installation and configuration to the playbooks.
It supports all famous cloud providers and Vagrant!
So we would be able to test it into the vagrant environment.
On localhost we would use classic volumes.

Describe alternatives you've considered

• cloudstor for docker-for-aws
• cloudstor docker-for-azure

... but those plugins are not open sourced and are cloud provider specific.

Additional context
Developing this feature would enable us to add more examples / pre-setupped services:

• portainer
• swarmprom
• ELK

Possible caveats:

• REX-Ray EBS for AWS is mono-AZ (contrary to cloudstor)