Hide auth_token and new_pass

mask_password will be used in oslo.messaging on the
message payload soon.

We mask auth_token and new_pass field to have the same behavior as
the current oslo.messaging fix_password method.

Change-Id: Ic7904793d29b323575b77a42f5c637c29e32cd43
Closes-Bug: #1378647
Merge "Hide auth_token and new_pass"