Add decoupled Python3 OMERO.web

[manics]

Renamed tasks/web-install.yml → tasks/web-install-py2.yml and made a few minor cleanups, but the existing behaviour should be unchanged. New variables (Python 3 only, otherwise ignored):

• omero_web_python3
• omero_web_python_addons
• ome.omero_web_apps is merged into this role: https://github.com/ome/ansible-role-omero-web-apps/pull/7 so all parameters from that role are now handled here

To avoid chaining python3 changes through the whole stack of roles this is self-contained.

Breaking changes when switching to Python 3 are listed in CHANGES.md

Closes https://github.com/ome/ansible-role-omero-web/issues/17 Closes https://github.com/ome/ansible-role-omero-web/issues/24 Closes https://github.com/ome/ansible-role-omero-web/issues/20

[snoopycrimecop]

Conflicting PR. Removed from build ANSIBLE-ROLES-merge#875. See the console output for more details. Possible conflicts:

• PR #18 manics 'Ensure config is flushed and systemd is setup before nginx'
  • tasks/web-nginx.yml

--conflicts Conflict resolved in build ANSIBLE-ROLES-merge#876. See the console output for more details.

[joshmoore]

Started worked in https://github.com/manics/ansible-role-omero-web/pull/1 -- a bit less clear as a variable since the file didn't exist previously.

[joshmoore]

This has been tested with https://github.com/ome/omero-web-docker/pull/42 and released as docker image openmicroscopy/omero-web:5.6.0-m3-1. Merging.

A couple of issues have been opened for follow-ups. If we had dev releases on galaxy, I'd propose an immediate 3.0.0.dev1 / 3.0.0-m1 release. Without, I'm not sure if we want the issues handled first.

cc: @manics @sbesson