setup.py: version number build from git describe

setup.py

@@ -1,9 +1,19 @@
 #!/usr/bin/python
 from setuptools import setup, find_packages
 import os
+import subprocess
+
+VERSION='0.1'
+
+def get_version():
+    if os.path.exists('.git'):
+        p = subprocess.Popen(['git','describe','--dirty'], stdout=subprocess.PIPE)
+        result = p.communicate()[0]
+        return result.split()[0].replace('-','.')
+    return VERSION
 
 setup(name='passerelle',
-        version='0.1',
+        version=get_version(),
         license='AGPLv3',
         description='',
         url='https://dev.entrouvert.org/projects/passerelle/',