safe_log Sanitize Passwords in List of Dicts

Sanitizes password fields found in lists of dicts for messages
before logging.

This change uses oslo.utils.strutils.mask_password to do it.

Change-Id: I7cd1e53e2ced7ebf9c5942b7a0dbbeb991acab4d
Closes-Bug: #1268459
Merge "safe_log Sanitize Passwords in List of Dicts"