Create version check utility and add to code check.

Fixes #70

util/versioncheck.py

@@ -0,0 +1,24 @@
+#!/usr/bin/python
+
+from subprocess import check_output as co
+from sys import exit
+
+# Actually run bin/mn rather than importing via python path
+version = 'Mininet ' + co( 'PYTHONPATH=. bin/mn --version', shell=True )
+version = version.strip()
+
+# Find all Mininet path references
+lines = co( "grep -or 'Mininet \w\.\w\.\w\w*' *", shell=True )
+
+error = False
+
+for line in lines.split( '\n' ):
+    if line and 'Binary' not in line:
+        fname, fversion = line.split( ':' )
+        if version != fversion:
+            print "%s: incorrect version '%s' (should be '%s')" % (
+                fname, fversion, version )
+            error = True
+
+if error:
+    exit( 1 )