updated package requirements

Author: Josh Watts

setup.py

@@ -5,7 +5,7 @@
       version="1.1.4",
       description="Instagram API client",
       license="MIT",
-      install_requires=["simplejson","httplib2"],
+      install_requires=["simplejson","httplib2","six"],
       author="Instagram, Inc",
       author_email="apidevelopers@instagram.com",
       url="http://github.com/Instagram/python-instagram",