Update to gRPC v1.6.0

The vendored gRPC is now v1.6.0, and the grpc-swift C shim layer compiles with versions of gRPC at least as far back as v1.4.5.

Simplify libz integration

Libz is now included as a source package that is built by the Swift Package Manager. This removes the need to add -lz to Package Manager builds of grpc-swift clients.

End-of-line for Swift 3.0 and swift-protobuf 0.9.24

Merge pull request #42 from johndpope/patch-1

Updates to Runme.sh