flask-restplus should be dropped in favor of flask-restx

[drawks]

While doing some testing of the CIFv5 stack I came across an exception in cif-httpd

Traceback (most recent call last):
  File "/usr/local/bin/cif-httpd", line 10, in <module>
    from cif.http.app import main
  File "/venv/cifv5/lib/python3.6/site-packages/cif/http/app.py", line 13, in <module>
    from flask_restplus import Api
  File "/venv/lib/python3.6/site-packages/flask_restplus/__init__.py", line 5, in <module>
    from .api import Api  # noqa
  File "/venv/cifv5/lib/python3.6/site-packages/flask_restplus/api.py", line 24, in <module>
    from werkzeug import cached_property
ImportError: cannot import name 'cached_property'

It looks like the flask-restplus module depends on an older version of werkzeug, not entirely unexpected as the version is pinned downrev to 0.16 in the requirements.txt. However when I looked a little bit further it appears that flask-restplus has been fully abandoned and the maintainers of the project have started releasing under a new forked project

It would be a good idea to update CIFv5 to use this newer module which would bring compatibility with the current release of werkzeug.