Better support for ES running on OpenShift

Sorry, I'm running OpenShift release-3, back when OPENSHIFT_LOG_DIR didn't existed yet. Maybe a better approach is to look on both dirs:

    path => [ "<%= ENV['OPENSHIFT_LOG_DIR'] %>*.log", "<%= ENV['OPENSHIFT_PRIMARY_CARTRIDGE_DIR'] %>/logs/*" ]

Please note that old log files may not be using that `.log` extension. Apache, for instance, writes to {access|error}_log. IMO, a simples `/*` does a better job.