New devops users role

This PR adds the devops team public keys. It uses the infra gp_role 'add_users' to add devops team keys to our servers.

The gp_roles need to be on the roles_path for this to work and the vars file needs to be included with, something like:

ansible.cfg:

roles_path=<path to gp_roles>/gp_roles

playbook.yml:

- hosts: <hosts>
  user: root
  roles:
    - add-devops-users

closes #8 (closed)