pin github3.py version

1.0.0+ does not work the same way. We should eventually upgrade, but for
now, pinning the dependency.

For some reason the less-than syntax isn't enough.

Author: Manishearth

setup.py

@@ -10,7 +10,7 @@
 
     packages=['homu'],
     install_requires=[
-        'github3.py<1.0',
+        'github3.py==0.9.6',
         'toml',
         'Jinja2',
         'requests',