Add 'version' command

Makefile

@@ -0,0 +1,6 @@
+GIT_COMMIT=$(shell git rev-list -1 HEAD)
+GIT_TAG=$(shell git tag --sort="-version:refname" | head -n 1)
+all:
+	go build -ldflags "-X main.GitCommit=${GIT_COMMIT} -X main.GitTag=${GIT_TAG}"
+
+