Merge branch 'master' of https://git.astron.nl/lofar2.0/tango into...

...tationcontrol/integration_test/devices/test_device_sst.py

...ationcontrol/integration_test/devices/test_device_unb2.py

...test/Tango_Controls-Automatic_polling_performance_test.md

..._performance_test/automatic_polling_performance_test.json

...c_polling_performance_test/monitoring_performance_test.py

tangostationcontrol/tangostationcontrol/toolkit/archiver.py

...ontrol/tangostationcontrol/toolkit/archiver_base_mysql.py

...oncontrol/tangostationcontrol/toolkit/archiver_base_ts.py

...l/tangostationcontrol/toolkit/archiver_config/__init__.py

...l/tangostationcontrol/toolkit/archiver_config/lofar2.json

...ol/tangostationcontrol/toolkit/attribute_polling_stats.py

tangostationcontrol/tangostationcontrol/toolkit/retriever.py