Make persistent data optional

[btzr-io]

If I disable cookies on chrome ( android ) I just see a blank page, but there are no errors / warnings.
We could add a fall back to make store data optional.
http://crocodillon.com/blog/always-catch-localstorage-security-and-quota-exceeded-errors

[btzr-io]

Access denied

try {
  localStorage = window.localStorage;
} catch(e) {
  // Access denied :-(
}

Full storage

try {
  localStorage.setItem(key, value);
} catch(e) {
  if (e.code == 22) {
    // Storage full, maybe notify user or do some clean-up
  }
}

[workhorsy]

This is a good idea. At a minimum we should show a warning that it wont work if cookies are disabled.