Added glide for vendoring dependencies.

- Docker to 1.13.x

CONTRIBUTING.md

@@ -16,21 +16,9 @@ cd watchtower
 ## Building and testing
 watchtower is a go application and is built with go commands. The following commands assume that you are at the root level of your repo.
 ```bash
-go get ./... # analyzes and retrieves package dependencies
-go build     # compiles and packages an executable binary, watchtower
-go test      # runs tests
-./watchtower # runs the application (outside of a container)
+go get -u github.com/Masterminds/glide # installs glide for vendoring
+glide install                          # retrieves package dependencies
+go build                               # compiles and packages an executable binary, watchtower
+go test                                # runs tests
+./watchtower                           # runs the application (outside of a container)
 ```
-
-### Building the docker image
-watchtower is packaged and distributed as a docker image. A [golang-builder](https://github.com/CenturyLinkLabs/golang-builder) is used to package the go code and its
-dependencies as a minimally-sized application. The application binary is then layered into to a minimal docker image (see `Dockerfile`), so that the entire image is <10MB.
-See `circle.yml` for further details.The following commands assume that you are at the root level of your repo (i.e. `watchtower/`).
-
-```bash
-docker pull centurylink/golang-builder:latest									# download the builder
-docker run -v $(pwd):/src centurylink/golang-builder:latest						# build the minimal binary
-docker build -t <yourfork>/watchtower:latest .									# build the docker image
-docker run -v /var/run/docker.sock:/var/run/docker.sock <yourfork>/watchtower	# run the application (inside of a container)
-```
-