Bug 894121 - Using MCC automatically selects wrong timezone

- Update timezone when sim unlocked
- Only set 'user-selected' setting if user handles the selectors
Please avoid boolean trap here,
http://ariya.ofilabs.com/2011/08/hall-of-api-shame-boolean-trap.html

Would be better
```js
function updateTZ(tz, options) {
  if (options.updateUserSelected) {
      settings.createLock().set({'time.timezone.user-selected': tz.id});
  }
}
```