frontend logging: keep openshift_log (bug 1069837)

https://bugzilla.redhat.com/show_bug.cgi?id=1069837
  -DOpenShiftFrontendSyslogEnabled disables openshift_log entries

When the -DOpenShiftFrontendSyslogEnabled cmdline option is added to the
node host httpd in order to direct gear logs to syslog, it stops writing
openshift_log entries. This is what the idler uses to assess whether a
gear is inactive or not, so it should keep writing this log.
Merge pull request #4820 from sosiouxme/frontend-logging

Merged by openshift-bot