Add requirement for enum backwards compatibility

setup.py

@@ -10,7 +10,8 @@ setup(
         exclude=["*.tests", "*.tests.*", "tests.*", "tests"]),
     package_data={
         '': ['*.md', 'LICENSE', 'README'],
-    }
+    },
+    install_requires=['enum34>=1.1.3'],
     license='GNU General Public License 3',
     description="A fork of pygov focused on USDA nutritional database API",
     long_description=open('README.md').read(),