Remove UpgradeCheckTest.testNoResponse from the unit tests
Add UpgradeCheckTest.testNoResponse to the OmeroJava integration tests
Clean up UpgradeCheckTest integration test
Fallback to using OMERO.test for the integration agent
Add unit and integration tests for the upgrade_checker in OMERO.py
Use proper copyright
Remove doctest in favor of pytest
Restore doctest as minimal documentation
Merge pull request #3065 from sbesson/upgradechecktest

Split UpgradeCheck unit and integration tests