FIX for #297 (#307)

There was a problem when `load_json(self.client.request('GET', path))['resources']` is null, as is later expected to be iterated. Therefore, I added a default empty list as output value for that property call.

openshift/dynamic/client.py

@@ -715,7 +715,7 @@ def get_resources_for_api_version(self, prefix, group, version, preferred):
         subresources = {}
 
         path = '/'.join(filter(None, [prefix, group, version]))
-        resources_response = load_json(self.client.request('GET', path))['resources']
+        resources_response = load_json(self.client.request('GET', path))['resources'] or []
 
         resources_raw = list(filter(lambda resource: '/' not in resource['name'], resources_response))
         subresources_raw = list(filter(lambda resource: '/' in resource['name'], resources_response))