updated concepts and added six to reqs

docs/concepts.rst

@@ -161,7 +161,7 @@ and be less than 200 characters long.
 
 It's optional for a backend implementation to understand this - after all,
 it's only important at scale, where you want to shard the two types differently
-- but it's present nonetheless. For more on scaling, and how to handle channel
+— but it's present nonetheless. For more on scaling, and how to handle channel
 types if you're writing a backend or interface server, read :doc:`scaling`.
 
 Groups

setup.py

@@ -10,4 +10,7 @@ setup(
     license='BSD',
     packages=find_packages(),
     include_package_data=True,
+    install_requires=[
+        'six',
+    ]
 )