Empty database should be initialised when OMERO.server already installed

[manics]

For example, if you run this playbook PostgreSQL will be installed, OMERO.server will be downloaded and symlinked, but the database initialisation will fail because it can't be accessed.

- hosts: omero-database
  roles:
    - role: openmicroscopy.postgresql
  vars:
    postgresql_users_databases:
    - user: omero
      password: omero
      databases: [omero]
    postgresql_version: "9.6"

- hosts: omero-server
  roles:
    - role: openmicroscopy.omero-server
    - role: openmicroscopy.omero-web
  vars:
    omero_server_dbhost: "{{ hostvars['omero-database'].ansible_eth0.ipv4.address }}"

The following must be added to allow external access to postgres:

    postgresql_server_listen: "'*'"
    postgresql_server_auth:
    - database: omero
      user: omero
      address: 0.0.0.0/0

If this is done and the playbook rerun the role will fail- OMERO.server appears to be installed so the role attempts to start it, which fails since the omero database exists but is empty.