installation: kombu and ceery troubles

[tiborsimko]

Latest reana-commons leads to kombu/celery incompatibility issue which makes e.g. r-j-controller to fail.

How to reproduce:

$ mkvirtualenv rjc
$ pip install --no-cache-dir .
...
Collecting celery<4.3,>=4.1.0 (from reana-commons==0.5.0.dev20190321)
...
Collecting kombu<5.0,>=4.2.0 (from reana-commons==0.5.0.dev20190321)
...
celery 4.2.2 has requirement kombu<4.4,>=4.2.0, but you'll have kombu 4.4.0 which is incompatible.
$ pip freeze | grep -E '(kombu|celery)'
celery==4.2.2
kombu==4.4.0

Note the warning phrase about celery/kombu version incompatibility. We are using:

$ git grep -E '(celery|kombu)' setup.py
setup.py:    'celery>=4.1.0,<4.3',
setup.py:    'kombu>=4.2.0,<5.0',

Apparently pip does not resolve appropriate versions well.

Let us amend the version requirements to get rid of this problem, which will also help other REANA components.

It would be also good to add a working test for kombu/celery to avoid this happening in the future.

(P.S. We could even consider a sort of "integration test" capturing the pip install output and looking for phrase which is incompatible 😉 Might help in catching other problems of this kind in a general fashion here and in the other REANA components. )