The indentation seems to be off, but I think it would be preferable to default to  "./storm/storm-" + stormVersion + "/", but provide a configuration that would override this so we could have almost any directory structure inside storm. Something like

String stormHomeInZip = (String)_stormConf.get("storm.home.in.zip");
if (stormHomeInZip == null) {
  if ("Unknown".equals(stormVersion)) {
      stormHomeInZip = "storm";
  } else {
    stormHomeInZip = "storm-"+stormVersion;
  }
}

we could then use stormHomeInZip everywhere.