title: add date to log filename with log4j
body: <p>I would like to add to my log filename the date.
  For exemple if my  filename is "jobfile", I will have "jobfile20170802". Below is my configuration file :</p>
  
  <pre><code>    log4j.rootLogger=debug, R
  log4j.appender.R=org.apache.log4j.RollingFileAppender
  log4j.appender.R.File=C:/TFS/PID/Dev/CRM/Logs/Dev/talend_crmJobs.log
  log4j.appender.R.layout=org.apache.log4j.PatternLayout
  log4j.appender.R.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss}| [%-5p]| %c{1} | %m%n
  </code></pre>