MINOR: Simplified attributes relating to EventLogsCollection.
Renamed EventLogModifier to EventLogManager.  Modified EventLogsSection.MachineName property to return "." (= local machine) if no name is explicitly specified in the config file).  This allowed EventLogManager.CreateEventLogsAndSources and RemoveEventLogsAndSources to be simplified - no longer need separate paths for local and remote machines.
Added ListEventLogsAndSources method.