Add build version and a version command

Makefile

@@ -3,6 +3,7 @@ REPOROOT = $(abspath $(dir $(THIS_MAKEFILE)))
 TEST_PACKAGES = $(subst $(REPOROOT)/src/,,$(shell go list -f '{{if gt (len .TestGoFiles) 0}}{{.Dir}}{{end}}' ./...))
 
 export GOPATH := $(REPOROOT)/
+export VERSION ?= DEVELOPMENT
 export GOCMD ?= go
 
 .PHONY: all
@@ -16,7 +17,7 @@ clean:
 
 .PHONY: ankh
 ankh:
-	cd $(REPOROOT)/src/ankh/cmd/ankh; $(GOCMD) install
+	cd $(REPOROOT)/src/ankh/cmd/ankh; $(GOCMD) install -ldflags "-X main.AnkhBuildVersion=$(VERSION)"
 
 .PHONY: install
 install: ankh

release.bash

@@ -1,8 +1,14 @@
 #!/bin/bash
 
+if [ -z "$VERSION" ] ; then
+	echo "Must provide VERSION"
+	exit 1
+fi
+
+make clean || exit 1
+
 release_dir=release
 mkdir -p $release_dir
-rm -f $release_dir/*
 
 function release() {
 	export GOOS=$1

src/ankh/cmd/ankh/main.go

@@ -23,6 +23,8 @@ import (
 	"ankh/util"
 )
 
+var AnkhBuildVersion string
+
 var log = logrus.New()
 
 func logExecuteAnkhFile(ctx *ankh.ExecutionContext, ankhFile ankh.AnkhFile) {
@@ -331,6 +333,11 @@ func main() {
 		})
 	})
 
+	app.Command("version", "Show version info", func(cmd *cli.Cmd) {
+		fmt.Println(AnkhBuildVersion)
+		os.Exit(0)
+	})
+
 	app.Run(os.Args)
 }