Run flake8 in Travis and make code PEP8 compliant. (#387)

test/jenkins_tests/multi_node_tests/test_0.py

@@ -3,11 +3,13 @@ import time
 
 import ray
 
+
 @ray.remote
 def f():
   time.sleep(0.1)
   return ray.services.get_node_ip_address()
 
+
 if __name__ == "__main__":
   ray.init(redis_address=os.environ["RAY_REDIS_ADDRESS"])
   # Check that tasks are scheduled on all nodes.