Parse exceptions from openstacksdk

When parsing exceptions from openstacksdk, exc.details is
desired to contain error message, but sometimes error may
exist in exc.message. Openstacksdk's HttpException has __str__
method to handle error message, so in senlinclient HttpException
object can show the right error message.

Change-Id: I9246ed3d47151ebb8e03cd13134d58749cd35785
Closes-bug: #1541217

senlinclient/common/exc.py

@@ -240,7 +240,7 @@ def parse_exception(exc):
             record = {
                 'error': {
                     'code': exc.http_status,
-                    'message': exc.details,
+                    'message': exc,
                 }
             }
     elif isinstance(exc, reqexc.RequestException):