Avoid generating 'No handlers could be found for logger "elasticsearch"' errors

by installing no-op logging handler per <https://docs.python.org/2/howto/logging.html#configuring-logging-for-a-library>.

elasticsearch/__init__.py

@@ -4,6 +4,17 @@ VERSION = (1, 2, 0)
 __version__ = VERSION
 __versionstr__ = '.'.join(map(str, VERSION))
 
+import sys
+
+if (2, 7) <= sys.version_info < (3, 2):
+    # On Python 2.7 and Python3 < 3.2, install no-op handler to silence
+    # `No handlers could be found for logger "elasticsearch"` message per
+    # <https://docs.python.org/2/howto/logging.html#configuring-logging-for-a-library>,
+    # <https://docs.python.org/3/howto/logging.html#configuring-logging-for-a-library>:
+    import logging
+    logger = logging.getLogger('elasticsearch')
+    logger.addHandler(logging.NullHandler())
+
 from .client import Elasticsearch
 from .transport import Transport
 from .connection_pool import ConnectionPool, ConnectionSelector, \