include version and commit hash at compile time

when using makefile, version is set to "git". Currently  printed on
start, but an about page in the web UI will be added.

Makefile

@@ -28,6 +28,9 @@ mail:
 	echo "Generating email html"
 	python3 mail/generate.py
 
+version:
+	python3 version.py git version.go
+
 compile:
 	echo "Downloading deps"
 	go mod download
@@ -42,8 +45,8 @@ copy:
 install:
 	cp -r build $(DESTDIR)/jfa-go
 
-all: configuration sass mail compile copy
-headless: configuration sass-headless mail-headless copy
+all: configuration sass mail version compile copy
+headless: configuration sass-headless mail-headless version compile copy