Merge pull request #569 from nathanielmanistaatgoogle/reorganize-python

src/python/interop/interop/methods.py

src/python/interop/interop/server.py

src/python/src/grpc/__init__.py

src/python/src/grpc/_adapter/__init__.py

...grpc/_adapter/_blocking_invocation_inline_service_test.py

src/python/src/grpc/_adapter/_c.c

src/python/src/grpc/_adapter/_c_test.py

src/python/src/grpc/_adapter/_call.c

src/python/src/grpc/_adapter/_call.h

src/python/src/grpc/_adapter/_channel.c

src/python/src/grpc/_adapter/_channel.h

src/python/src/grpc/_adapter/_common.py

src/python/src/grpc/_adapter/_completion_queue.c

src/python/src/grpc/_adapter/_completion_queue.h

src/python/src/grpc/_adapter/_datatypes.py

src/python/src/grpc/_adapter/_error.c

src/python/src/grpc/_adapter/_error.h

...apter/_event_invocation_synchronous_event_service_test.py

src/python/src/grpc/_adapter/_face_test_case.py

...ter/_future_invocation_asynchronous_event_service_test.py