all: Become a Go module (fixes #5148) (#5384)

* go mod init; rm -rf vendor

* tweak proto files and generation

* go mod vendor

* clean up build.go

* protobuf literals in tests

* downgrade gogo/protobuf

vendor/github.com/jackpal/gateway/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+
+go:
+  - 1.6.2
+  - tip
+
+allowed_failures:
+  - go: tip
+
+install:
+  - go get -d -v ./... && go install -race -v ./...
+
+script: go test -race -v ./...