Update for Python3

[staze]

With Python2 deprecated, it would be good to get this updated for Python3. I managed to get some of it working (by adding paranthesis for print statements, and changing the urlparse import statement), but then it just errors out:

[Mon Apr 27 09:59:25.642587 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975] [2020-04-27 09:59:25,639] ERROR in app: Exception on /products [GET]
[Mon Apr 27 09:59:25.642625 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975] Traceback (most recent call last):
[Mon Apr 27 09:59:25.642629 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/app.py", line 2447, in wsgi_app
[Mon Apr 27 09:59:25.642638 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     response = self.full_dispatch_request()
[Mon Apr 27 09:59:25.642641 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/app.py", line 1952, in full_dispatch_request
[Mon Apr 27 09:59:25.642644 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     rv = self.handle_user_exception(e)
[Mon Apr 27 09:59:25.642646 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/app.py", line 1821, in handle_user_exception
[Mon Apr 27 09:59:25.642649 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     reraise(exc_type, exc_value, tb)
[Mon Apr 27 09:59:25.642652 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/_compat.py", line 39, in reraise
[Mon Apr 27 09:59:25.642655 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     raise value
[Mon Apr 27 09:59:25.642658 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/app.py", line 1950, in full_dispatch_request
[Mon Apr 27 09:59:25.642661 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     rv = self.dispatch_request()
[Mon Apr 27 09:59:25.642686 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/lib64/python3.6/site-packages/flask/app.py", line 1936, in dispatch_request
[Mon Apr 27 09:59:25.642690 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     return self.view_functions[rule.endpoint](**req.view_args)
[Mon Apr 27 09:59:25.642692 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/asus/margarita/margarita.py", line 146, in products
[Mon Apr 27 09:59:25.642695 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     return json_response({'products': sprodlist, 'branches': catalog_branches.keys()})
[Mon Apr 27 09:59:25.642698 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/local/asus/margarita/margarita.py", line 52, in json_response
[Mon Apr 27 09:59:25.642700 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     return Response(json.dumps(r), status=200, mimetype='application/json')
[Mon Apr 27 09:59:25.642703 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/lib64/python3.6/json/__init__.py", line 231, in dumps
[Mon Apr 27 09:59:25.642705 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     return _default_encoder.encode(obj)
[Mon Apr 27 09:59:25.642708 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/lib64/python3.6/json/encoder.py", line 199, in encode
[Mon Apr 27 09:59:25.642711 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     chunks = self.iterencode(o, _one_shot=True)
[Mon Apr 27 09:59:25.642722 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/lib64/python3.6/json/encoder.py", line 257, in iterencode
[Mon Apr 27 09:59:25.642725 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     return _iterencode(o, 0)
[Mon Apr 27 09:59:25.642728 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]   File "/usr/lib64/python3.6/json/encoder.py", line 180, in default
[Mon Apr 27 09:59:25.642730 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]     o.__class__.__name__)
[Mon Apr 27 09:59:25.642734 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975] TypeError: Object of type 'dict_keys' is not JSON serializable
[Mon Apr 27 09:59:25.642771 2020] [wsgi:error] [pid 41828:tid 139685827593984] [remote 10.174.12.93:59975]