grpc: use RegisterService instead of RegisterAsyncService.
grpc: use RegisterService instead of RegisterAsyncService.

grpc 0.14.0-dev does not have RegisterAsyncService anymore,
and the gRPC examples that use async now use RegisterService
instead of RegisterAsyncService.

Lartza/mumble,Lartza/mumble,LuAPi/mumble,SuperNascher/mumble,Lartza/mumble,LuAPi/mumble,Lartza/mumble,LuAPi/mumble,Lartza/mumble,LuAPi/mumble,SuperNascher/mumble,Lartza/mumble,SuperNascher/mumble,SuperNascher/mumble,SuperNascher/mumble,LuAPi/mumble,SuperNascher/mumble,Lartza/mumble,Lartza/mumble,LuAPi/mumble,LuAPi/mumble,LuAPi/mumble,SuperNascher/mumble,SuperNascher/mumble,LuAPi/mumble,SuperNascher/mumble