Add OSSN-0024 - Sensitive data exposure in logfiles

This adds a new note to cover a sensitive data exposure issue in
logfiles.  Passwords and tokens can be logged by python-keystoneclient
when the log level is set to DEBUG.

Change-Id: I1435dab3f443b39453e1907c647002f8a35df9cb
Closes-Bug: 1004114
Merge "Add OSSN-0024 - Sensitive data exposure in logfiles"