Read version from .VERSION if not git dir

* Added a script for parsing the .VERSION file.
* Updated cli Makefile to attempt .VERSION read if not git dir. .VERSION
has a slug that will be populated by `git archive`.

Author: dopey

.version.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+read -r firstline < .VERSION
+last_half="${firstline##*tag: }"
+if [[ ${last_half::1} == "v" ]]; then
+    version_string="${last_half%%[,)]*}"
+fi
+echo "${version_string:-v0.0.0}"

Makefile

@@ -2,5 +2,11 @@ all: build lint test
 
 .PHONY: all
 
+# Version flags to embed in the binaries
+VERSION ?= $(shell [ -d .git ] && git describe --tags --always --dirty="-dev")
+# If we are not in an active git dir then try reading the version from .VERSION.
+# .VERSION contains a slug populated by `git archive`.
+VERSION := $(or $(VERSION),$(shell ./.version.sh .VERSION))
+
 -include make/common.mk
 -include make/docker.mk