L2SS-1793: Poll asynchronously

README.md

tangostationcontrol/VERSION

...tationcontrol/tangostationcontrol/clients/comms_client.py

tangostationcontrol/tangostationcontrol/common/asyncio.py

...tationcontrol/devices/base_device_classes/async_device.py

...tationcontrol/devices/base_device_classes/lofar_device.py

...tationcontrol/devices/base_device_classes/opcua_device.py

tangostationcontrol/test/common/test_asyncio.py

...rol/test/devices/base_device_classes/test_lofar_device.py

...tationcontrol/test/devices/test_station_manager_device.py