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.

version.py

@@ -0,0 +1,20 @@
+import subprocess
+import sys
+import os
+try:
+    version = sys.argv[1].replace('v', '')
+except IndexError:
+    version = "git"
+
+commit = subprocess.check_output("git rev-parse --short HEAD".split()).decode("utf-8").rstrip()
+
+file = f'package main; const VERSION = "{version}"; const COMMIT = "{commit}";'
+
+try:
+    writeto = sys.argv[2]
+except IndexError:
+    writeto = "version.go"
+
+with open(writeto, 'w') as f:
+    f.write(file)
+