Print raw response when JSON fails to parse

If the response to the Tautulli API fails to parse correctly include the 
raw output in the message to make it easier to diagnose when the 
response isn't actually raw JSON from a Tautulli server (e.g. a proxy 
server).

killstream/kill_stream.py

@@ -268,7 +268,9 @@ class Tautulli:
         try:
             response_json = response.json()
         except ValueError:
-            print("Failed to parse json response for Tautulli API cmd '{}'".format(cmd))
+            print(
+                "Failed to parse json response for Tautulli API cmd '{}': {}"
+                .format(cmd, response.content))
             return
 
         if response_json['response']['result'] == 'success':