Fix PEP8 whitespace issues

autopep8 -r polymorphic/ example/ -i
--select=E112,E113,E115,E116,E122,E123,E125,E127,E128,E201,E202,E203,E211,E225,E226,E227,E228,E231,E251,E261,E262,E271,E272,E273,E274,E301,E302,E303,E304,E309,E711,E713,W291,W293,W391
--exclude migrations,south_migrations

(line conditiation fixes: E123,E125,E122,E127,E128)

example/example/settings.py

@@ -75,7 +75,7 @@ INSTALLED_APPS = (
     'pexp',             # this Django app is for testing and experimentation; not needed otherwise
 )
 
-if django.VERSION >= (1,7):
+if django.VERSION >= (1, 7):
     TEST_RUNNER = 'django.test.runner.DiscoverRunner'  # silence system checks
 
 # Logging configuration