Add a Makefile with a few targets. The default is 'build'. The build

target calls the new version-at-commit.sh script which will
automatically populate the version variable inside the Headscale binary.

Once we start tagging releases on the git tree, that will come in handy.

The Makefile also has a 'test' target (does nothing yet, no tests yet)
and a 'dev' target, which runs linters, tests, and finally builds.

Makefile

@@ -0,0 +1,24 @@
+# Calculate version
+version = $(shell ./scripts/version-at-commit.sh)
+
+build:
+	go build -ldflags "-s -w -X main.version=$(version)" cmd/headscale/headscale.go
+
+dev: lint test build
+
+test:
+	go test -coverprofile=coverage.out
+
+coverprofile_func:
+	go tool cover -func=coverage.out
+
+coverprofile_html:
+	go tool cover -html=coverage.out
+
+lint:
+	golint
+	golangci-lint run
+
+compress: build
+	upx --brute cmd/headscale/headscale
+