Implementation of PolicyService.

src/common/tools/object_factory/PolicyRule.py

src/context/client/ContextClient.py

src/context/service/database/PolicyRuleModel.py

src/context/service/grpc_server/Constants.py

src/context/service/grpc_server/ContextService.py

...context/service/grpc_server/ContextServiceServicerImpl.py

src/context/tests/Objects.py

src/context/tests/test_unitary.py

src/policy/client/PolicyClient.py

src/policy/client/__init__.py