Cache example is write-only

[alexlamsl]

It may makes sense for the example to call .probe() so cached OCSP responses get reused.

var cache = new ocsp.Cache();

var server = https.createServer({
  cert: cert,
  key: key
}, function(req, res) {
  res.end('hello world');
});

server.on('OCSPRequest', function(cert, issuer, cb) {
  ocsp.getOCSPURI(cert, function(err, uri) {
    if (err)
      return cb(err);

    var req = ocsp.request.generate(cert, issuer);
    cache.probe(req.id, function(err, response) {
      if (err)
        return cb(err);

      if (response)
        return cb(null, response);

      var options = {
        url: uri,
        ocsp: req.data
      };

      cache.request(req.id, options, cb);
    });
  });
});