Cut a minor release for https://github.com/grpc-ecosystem/grpc-gateway/issues/495

[johanbrandhorst]

Release 1.3.0 has a small bug in the streaming responses in that the delimiter is no longer kept when the marshaller doesn't implement the delimiter interface. This was fixed in #497, and I'd appreciate a minor version bump with this fix included.

[tmc]

Release 1.3.1 has been tagged.