Factor out need for six.

This causes a slight performance penatly for every query evaluation
in older versions of python, but this seems acceptable.

querylist/querylist.py

@@ -1,7 +1,5 @@
 from __future__ import absolute_import
 
-from six import iteritems
-
 from .betterdict import BetterDict
 from .fieldlookup import field_lookup
 
@@ -76,7 +74,7 @@ def _check_element(self, lookup_strings, instance):
         object.
 
         """
-        for q, val in iteritems(lookup_strings):
+        for q, val in lookup_strings.items():
             if not field_lookup(instance, q, val, True):
                 return False
 

requirements.txt

@@ -1,5 +1,3 @@
-six==1.9.0
-
 # Testing requirements.
 coveralls==0.4.1
 flake8==2.3.0

setup.py

@@ -28,9 +28,6 @@
                 'also provides BetterDict, a dot lookup/assignment capable '
                 'wrapper for dicts that is 100% backwards compatible.',
     packages=find_packages(),
-    install_requires=[
-        'six>=1.9.0,<1.10',
-    ],
     tests_require=[
         'nose>=1.3.6,<1.4',
         'spec>=1.2.2,<1.3',