Make a Dockerfile and a make image command

Dockerfile

@@ -0,0 +1,5 @@
+FROM scratch
+MAINTAINER Romain Baugue <romain.baugue@elwinar.com>
+
+COPY rambler /
+CMD ["/rambler", "apply", "-a"]

Makefile

@@ -1,5 +1,5 @@
 TARGETS="windows/amd64,windows/386,darwin/amd64,darwin/386,linux/amd64,linux/386"
-LDFLAGS="-X main.VERSION=`git describe --tags`"
+LDFLAGS="-X main.VERSION=`git describe --tags` -s -linkmode external -extldflags -static -w"
 PKG="github.com/elwinar/rambler"
 
 default: build
@@ -17,6 +17,10 @@ fetch: ## Fetch the dependencies
 help: ## Get help
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-10s\033[0m %s\n", $$1, $$2}'
 
+.PHONY: image
+image: ## Build the docker image
+	docker build . -t elwinar/rambler --no-cache
+
 .PHONY: release
 release: ## Build the release files
 	go get github.com/karalabe/xgo