Ran 2to3 on pillar + some manual fixups

The 'manual fixups' are:

- incorrect use of dict.items() where dict.iteritems() was meant; this
  results in list(dict.items()), which I changed to dict.items().
- removal of 'from __future__ import' lines, which 2to3 changes into
  empty lines; I removed the empty lines.

pillar/extension.py

@@ -18,9 +18,7 @@ can then be registered to the application at app creation time:
 import abc
 
 
-class PillarExtension(object):
-    __metaclass__ = abc.ABCMeta
-
+class PillarExtension(object, metaclass=abc.ABCMeta):
     @abc.abstractproperty
     def name(self):
         """The name of this extension.