This change makes the etcd package compatible with the existing Go
ecosystem for module versioning.
Used this tool to update package imports:
https://github.com/KSubedi/gomove
If 'StartEtcd' returns before starting gRPC server
(e.g. mismatch snapshot, misconfiguration),
receiving from grpcServerC blocks forever. This patch
just closes the channel to not block on grpcServerC,
and proceeds to next stop operations in Close.
This was masking the issues in https://github.com/coreos/etcd/issues/7834
Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>