Remove ordereddict from requirements

Ordereddict was required for py26 support. Since we have
dropped support for py26 (we are no longer gating on it) we
should remove it as a requirement and remove references
to it in the code.

Change-Id: I5077039f95f65ece7992f14ffe14f149f73a2174
Partial-bug: 1445827

glance_store/_drivers/swift/utils.py

@@ -15,10 +15,7 @@
 import ConfigParser
 import logging
 
-try:
-    from collections import OrderedDict
-except ImportError:
-    from ordereddict import OrderedDict
+from collections import OrderedDict
 
 from oslo_config import cfg
 

requirements.txt

@@ -12,6 +12,3 @@ eventlet>=0.13.0 #s3
 six>=1.4.1
 
 jsonschema>=2.0.0,<3.0.0
-
-# py2.6 compat
-ordereddict