Micro-service deployment & NGINX configuration

[sbesson]

The deployment of the image-region micro-service was added in #430 via the extension the idr-omero-readonly.yml playbook.

Because the role is internally patching the NGINX configuration created by the ome.omero_web role, a possible issue is that executing the idr-omero-web.yml playbook in isolation can revert this change. This is effectively what happened in #435 in order to deploy an OMERO.map configuration change

There are a few possible options to make the systems more robust:

• either consider the sub-playbooks should no longer be executed individually and only idr-01-install-idr.yml should be executed when modifying a deployment. An advantage of this approach is that it should ensure that all playbooks are run in the order. A downside is the execution time. In particular, tackling Reconsider systematic usage of update_cache in Ansible roles #433 might be useful if this is the approach
• move the ome.omero_ms_image_region role to the idr-omero-web.yml playbook so that it can always be executed after the ome.omero_web role and prevent any regression in the NGINX configuration

/cc @dominikl