Mention erroneous workers in process process completion email notification

arkindex/ponos/serializers.py

arkindex/ponos/tasks.py

arkindex/ponos/tests/test_api.py

arkindex/process/tests/test_signals.py

arkindex/project/config.py

arkindex/project/tests/config_samples/defaults.yaml

arkindex/project/tests/config_samples/override.yaml

arkindex/project/triggers.py

arkindex/templates/process_completion.html