replaced e.message

BaseException.message has been deprecated as of Python 2.6.

http://legacy.python.org/dev/peps/pep-0352/

Replaced e.message with six.text_type(e) (uses unicode with
Python 2.x and str with Python 3.x).

Change-Id: I89aa278c337dd5985d6de28563b1d6e64ce4f95a