Fix murmur3 import, better murmur3 failure handling

cassandra/policies.py

@@ -1,8 +1,11 @@
 from itertools import islice, cycle, groupby, repeat
+import logging
 from random import randint
 
 from cassandra import ConsistencyLevel
 
+log = logging.getLogger(__name__)
+
 class HostDistance(object):
     """
     A measure of how "distant" a node is from the client, which