Verify the token is not anything empty, not just "not an empty string"

If you pass an empty list, tuple, False, 0, whatever.. it will assume th
token is valid, which it isn't.

logzio/handler.py

@@ -18,7 +18,7 @@ class LogzioHandler(logging.Handler):
                  url="https://listener.logz.io:8071",
                  debug=False):
 
-        if token is "":
+        if not token:
             raise LogzioException("Logz.io Token must be provided")
 
         self.logzio_type = logzio_type