Add OrderedDict dependency. Make sure hooks are run in a deterministic order

pre_commit/ordereddict.py

@@ -0,0 +1,10 @@
+from __future__ import absolute_import
+
+# This module serves only as a shim for OrderedDict
+
+try:
+    from collections import OrderedDict
+except ImportError:
+    from orderddict import OrderedDict
+
+__all__ = (OrderedDict.__name__,)