Log reason for connection failed exception

Change-Id: Idfdf43762fc3bd9abef33110cccd37d2d2f50df4

neutronclient/client.py

@@ -149,6 +149,7 @@ class HTTPClient(httplib2.Http):
             # Wrap the low-level connection error (socket timeout, redirect
             # limit, decompression error, etc) into our custom high-level
             # connection exception (it is excepted in the upper layers of code)
+            _logger.debug("throwing ConnectionFailed : %s", e)
             raise exceptions.ConnectionFailed(reason=e)
         finally:
             # Temporary Fix for gate failures. RPC calls and HTTP requests