Fixed flake8 errors for kafka/tools/assigner/actions/demote.py

The flake8 errors were part of the reason why Travis build was failing for PR #91 for linkedin/kafka-tools. The other factor was tox running into an upstream python bug [1] for which PR #94 has been raised. I confirmed that after these 2 factors were eliminated, the build passes [2].

[1] https://bugs.python.org/issue10496
[2] akashvacher@2228e65

kafka/tools/assigner/actions/demote.py

@@ -31,9 +31,8 @@ def __init__(self, args, cluster):
     def _add_args(cls, parser):
         parser.add_argument(
             '-b', '--brokers', type=int, help='List of broker ids to demote', required=True, nargs='*')
-        parser.add_argument('-t', '--topics', required=False, nargs='*', help=\
-            'Optional list of topics to use. If not specified, leadership of all topics lead by the brokers to ' \
-            'demote will be changed.')
+        parser.add_argument('-t', '--topics', required=False, nargs='*',
+                            help='Optional list of topics to use. If not specified, leadership of all topics lead by the brokers to demote will be changed.')
 
     def process_cluster(self):
         brokers_to_demote = set(self.args.brokers)