Do not shut down group if on-going import

Do not shut it down when removing the group from the display
when there is an on-going import in that group.
Remove group only if no on-going import
Fix for 11674 - script doc links
Remove tabs and whitespace
Remove "settings" term.
Remove whitespace.
Remove "settings" term.
Use pytest to bring OmeroWeb unit tests in line with OmeroPy

Unit tests for OmeroWeb can now be run with:

    ./build.py -f components/tools/OmeroWeb/build.xml test
Allow instantiation when config.xml is missing

If config.xml is missing it should still be possible to run through our
Django settings configuration.  An empty dictionary of settings
should suffice.
Fix flake8 errors in setup.py
Add tools/target/lib/python to setup.py
Added test_simple as a smoke test from OmeroPy/test/integration/
Add OmeroPy to the PYTHONPATH in setup.py

This allows us to use the OmeroPy integration test libraries, fixtures
and infrastructure in the OmeroWeb tests.
More robust searching for the OmeroPy directory
Add a README to mainly document test running
Update integration test target
Fix flake8 errors
Ensure components/tools/OmeroWeb/test/unit is hitting flake8
Also run OMERO.web unit tests
Fix flake8 errors