Make storage.utils.keyify py3k compatible

In the storage.utils.keyify function, there is proxy object, that wraps
each item and makes it comparable via __cmp__ function. Since Python 3
old-fashion `cmp` is totally removed and only rich comparison functions
should be used (i.e. __lt__, __gt__).

Partially-implements: blueprint py3k-support
Change-Id: I36841fa33c7e49b8b14fb623d6859077e3d8b6f5

marconi/queues/storage/utils.py

@@ -97,11 +97,23 @@ def keyify(key, iterable):
         def __init__(self, obj):
             self.obj = obj
 
-        def __cmp__(self, other):
-            return cmp(self.obj[key], other.obj[key])
+        def __eq__(self, other):
+            return self.obj[key] == other.obj[key]
 
-        # TODO(zyuan): define magic operators to make py3 work
-        #     http://code.activestate.com/recipes/576653/
+        def __ne__(self, other):
+            return self.obj[key] != other.obj[key]
+
+        def __lt__(self, other):
+            return self.obj[key] < other.obj[key]
+
+        def __le__(self, other):
+            return self.obj[key] <= other.obj[key]
+
+        def __gt__(self, other):
+            return self.obj[key] > other.obj[key]
+
+        def __ge__(self, other):
+            return self.obj[key] >= other.obj[key]
 
     for item in iterable:
         yield Keyed(item)