Log events, including both user IDs when masquerading is in progress. The log
can be configured to log all events or only those while masquerading is in
progress or none. The log is expired after a configurable delay.

Note that this logs all events (or all masquerading events) even though this
feature only includes one report of one type of event.

Change-Id: I7a59d98b84b0527a55363b4d01448b9b1809aa9e
Signed-off-by: Jiri Baum <jiri@catalyst-au.net>