title: Zookeeper deletes logs on restart
body: <p>Everytime that I restart zookeeper it truncates the file <code>/var/log/zookeeper/instance/zookeeper.out</code>.<br />
  I would like to change this behaviour in a way that it always appends the lines to that log file so that I can see for example the cause of a crash.</p>
  <p>Zookeeper version: 3.5.4-beta</p>