Use a machine fingerprint for agent identification

arkindex/metrics/tests/test_metrics_api.py

arkindex/ponos/migrations/0017_remove_agents.py

arkindex/ponos/migrations/0018_agent_fingerprint.py

arkindex/ponos/models.py

arkindex/ponos/serializer_fields.py

arkindex/ponos/tests/tasks/test_partial_update.py

arkindex/ponos/tests/tasks/test_retrieve.py

arkindex/ponos/tests/tasks/test_update.py

arkindex/ponos/tests/test_models.py

arkindex/process/tests/process/test_create.py

arkindex/process/tests/worker_runs/test_delete.py

arkindex/process/tests/worker_runs/test_partial_update.py

arkindex/process/tests/worker_runs/test_retrieve.py

arkindex/process/tests/worker_runs/test_update.py