title: release lock on log file log4j after process is completed
body: <p>I am using lsf4j on top of log4j to log events in my app. I have a custom file appender that is being used to log events to multipule log files, a main log file and log file for each process instance my app manages. 
  I also have a scheduled purge task that runs in parallel and its purpose is to clear all log files of completed processes but when trying to delete those files the following ERROR is thrown: "The process cannot access the file because it is being used by another process.".
  If I restart my app those files do get purged when the purge task runs, hence the reason is that the lock set by log4j is released only upon restart.
  I need a way to programmatically lift the lock on a log file given it`s name.</p>