Defined/Corrected skeleton for Slice component

src/slice/client/SliceClient.py

src/slice/proto/context_pb2.py

src/slice/proto/kpi_sample_types_pb2.py

src/slice/proto/service_pb2.py

src/slice/proto/slice_pb2.py

src/slice/requirements.in

src/slice/service/SliceService.py

src/slice/service/SliceServiceServicerImpl.py

src/slice/service/__main__.py