This will never be the case now

As we are now using a two step parse and then object retrieval there is
no reason to check the values of these variables in the constructor.
Fix a typo and not recognising a list correctly
Update tests for project-dataset hierarchy
Update tests for project-dataset-image and tag hierarchy
Ensure basic OMERO.web environment is completely set up
Merge branch 'omeroweb-test-fixes' into show-extensions
Fix typo and expand explanation
Update tests for tagset-tag, tag and orphaned-image hierarchies
Fix bug in initial logic where Wells have no WellSamples

If we've been requested to show a Well and it has no WellSamples then
we now select the Plate as that's all we can resolve.
Update tests for all screen-plate-well related hierarchies
Update tests to cover illegal values
Switch from DOS to UNIX line endings
Merge branch 'omeroweb-test-fixes' into show-extensions
Make "integration" target only run integration (not unit) tests

With this commit OmeroPy and OmeroWeb "integration" targets from
`build.py` or Ant will only run integration tests.  This mirrors the
documented behaviour of using `setup.py` directly for either tools
component.  Collisions, where both a unit and integration test package
have the same name, are possible in the global build without this
change.
Merge branch 'omeroweb-test-fixes' into show-extensions
Move "show" integration test to the right package name
Use correct class name for "show" integration tests

Now that mega collisions with the unit tests are no longer happening we
can standardise these properly.