clean up unused nats code

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

vendor/google.golang.org/grpc/README.md

@@ -0,0 +1,57 @@
+#gRPC-Go
+
+[![Build Status](https://travis-ci.org/grpc/grpc-go.svg)](https://travis-ci.org/grpc/grpc-go) [![GoDoc](https://godoc.org/google.golang.org/grpc?status.svg)](https://godoc.org/google.golang.org/grpc)
+
+The Go implementation of [gRPC](http://www.grpc.io/): A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the [gRPC Quick Start](http://www.grpc.io/docs/) guide.
+
+Installation
+------------
+
+To install this package, you need to install Go and setup your Go workspace on your computer. The simplest way to install the library is to run:
+
+```
+$ go get google.golang.org/grpc
+```
+
+Prerequisites
+-------------
+
+This requires Go 1.5 or later.
+
+A note on the version used: significant performance improvements in benchmarks
+of grpc-go have been seen by upgrading the go version from 1.5 to the latest
+1.7.1.
+
+From https://golang.org/doc/install, one way to install the latest version of go is:
+```
+$ GO_VERSION=1.7.1
+$ OS=linux
+$ ARCH=amd64
+$ curl -O https://storage.googleapis.com/golang/go${GO_VERSION}.${OS}-${ARCH}.tar.gz
+$ sudo tar -C /usr/local -xzf go$GO_VERSION.$OS-$ARCH.tar.gz
+$ # Put go on the PATH, keep the usual installation dir
+$ sudo ln -s /usr/local/go/bin/go /usr/bin/go
+$ rm go$GO_VERSION.$OS-$ARCH.tar.gz
+```
+
+Constraints
+-----------
+The grpc package should only depend on standard Go packages and a small number of exceptions. If your contribution introduces new dependencies which are NOT in the [list](http://godoc.org/google.golang.org/grpc?imports), you need a discussion with gRPC-Go authors and consultants.
+
+Documentation
+-------------
+See [API documentation](https://godoc.org/google.golang.org/grpc) for package and API descriptions and find examples in the [examples directory](examples/).
+
+Status
+------
+GA
+
+FAQ
+---
+
+#### Compiling error, undefined: grpc.SupportPackageIsVersion
+
+Please update proto package, gRPC package and rebuild the proto files:
+ - `go get -u github.com/golang/protobuf/{proto,protoc-gen-go}`
+ - `go get -u google.golang.org/grpc`
+ - `protoc --go_out=plugins=grpc:. *.proto`