Add dependency on ordereddict for python 2.6

Author: rdunklau

setup.py

@@ -1,4 +1,5 @@
 import subprocess
+import sys
 from setuptools import setup, find_packages, Extension
 
 # hum... borrowed from psycopg2
@@ -17,6 +18,14 @@ def get_pg_config(kind, pg_config="pg_config"):
         extra_compile_args = ['-shared'],
         sources=['src/utils.c'])
 
+requires=[]
+
+if sys.version_info[0] == 2:
+    if sys.version.info[1] == 6:
+        requires.append("ordereddict")
+    elif sys.version.info[1] < 6:
+        sys.exit("Sorry, you need at least python 2.6 for Multicorn")
+
 setup(
  name='multicorn',
  version='__VERSION__',