Tweaks to NLog logger

I was having trouble using Nlog's pattern matching rules with the ServiceStack logging wrapper and ended up here.. http://stackoverflow.com/questions/3947136/problem-matching-specific-nlog-logger-name.

So I've added an option to use Full Type names (default false for backwards compatibility) and changed the internal logging impl to preserve call site information (so that logs are filled up with this "Foo.Bar.Baz.ScheduledTasks.Tasks.CleanDBTablesJob.Execute" instead of this "ServiceStack.Logging.NLogger.NLogLogger.InfoFormat")