add vendoring with go dep

vendor/github.com/influxdata/influxdb/releng/README.md

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+# influxdb/releng
+
+This directory and its subdirectories contain release engineering scripts to build source tarballs and packages, run unit tests in an isolated environment, and so on.
+The directory layout typically looks like:
+
+```
+├── Dockerfile
+├── build.bash
+└── fs
+    └── usr
+        └── local
+            └── bin
+                └── influxdb_tarball.bash
+```
+
+Where you only need to run `build.bash` (or other shell scripts in the root directory) with valid arguments to complete the step.
+All scripts in the root folders accept the `-h` flag to explain usage.
+
+The `fs` folder is overlaid on the Docker image so that is clear where each script for the Docker containers reside.
+Those scripts make assumptions about the environment which are controlled in the outer scripts (i.e. `build.bash`), so the scripts not intended to be run outside of Docker.
+
+By default, these scripts will use the "current" Go version as determined by `_go_versions.sh`.
+To use the "next" version of Go, set the environment variable GO_NEXT to a non-empty value.
+
+## source-tarball
+
+Generates a source tarball of influxdb that can be extracted to a new `GOPATH` such that you can `go build github.com/influxdata/influxdb/cmd/influxd`, etc., without manually setting linker flags or anything.
+
+## raw-binaries
+
+Builds the raw binaries for the various influxdb commands, and stores them in OS/architecture-specific tarballs in the provided destination path.
+
+## packages
+
+Given a source tarball and an archive of raw binaries, generates OS/architecture-specific packages (i.e. .deb and .rpm files).
+
+## unit-tests
+
+Given a source tarball, runs the influxdb unit tests in a clean Docker environment.