Stop using deprecated 'message' attribute in Exception

The 'message' attribute has been deprecated and removed
from Python3.
For more details, please check:
https://www.python.org/dev/peps/pep-0352/

Change-Id: I152e79352705a3e43ce464a8f087b0e93f072035

swift/common/middleware/x_profile/html_viewer.py

@@ -529,5 +529,5 @@ class HTMLViewer(object):
                                 --></a></td></tr>' % (app_path,
                                                       profile_id, nfls))
         except Exception as ex:
-            html.append("Exception:" % ex.message)
+            html.append("Exception:" % str(ex))
         return ''.join(html)