Add Binder playbook

[jraddaoui]

With stable/0.8.x and qa/0.9.x options. WIP.

Fixes #66.

[jraddaoui]

Hi @hakamine and @scollazo,

This is in a working state but I'd love to hear your thoughts about the 'stable' vs 'qa' situation. The issues I'm facing:

• Both require PHP 5 to work, that's why I'm adding only and Ubuntu Trusty option.
• Elasticsearch 1.x is used in stable while 5.x is used in qa.
• The Elastic ES Ansible role doesn't support ES < 2.x.
• Our ES role doesn't support ES 5.x.
• The Elastic ES role doesn't install Java 8 in Ubuntu 14.04 as it's not available by default in there.

Therefore, I have ended with two different playbooks and requirements instead of only a few var changes like I was hopping for.

Do you think I should create two different folders? Maybe 'binder-qa' and 'binder-stable'. Or do you have a better option?

Thanks.

[jraddaoui]

Depends on artefactual-labs/ansible-atom#19, I'll change the AtoM role version once that's merged and improve the readme(s) when we decide what to do with the 'stable' vs 'qa' situation.