cant depend on build-helper to have cdist.version module

Signed-off-by: Steven Armstrong <steven@icarus.ethz.ch>

setup.py

@@ -1,9 +1,20 @@
 from distutils.core import setup
-import cdist
 import os
 import re
 
 
+# Ensure version is present - the bundled/shipped version contains a static version,
+# the git version contains a dynamic version
+try:
+    import cdist.version
+except ImportError:
+    import subprocess
+    version = subprocess.getoutput('git describe')
+    with open('cdist/version.py', 'w') as fd:
+        fd.write('VERSION = "%s"\n' % version)
+
+import cdist
+
 def data_finder(data_dir):
     entries = []
     for name in os.listdir(data_dir):