Bug 1040271 - [L10n][SMS] Clean up mozL10n.get uses in SMS app

Ok, I didn't see that the sim could be empty.

Are you looking for something like this?
```
  var info = [];
  var simId = Settings.getSimNameByIccId(iccId);
  var operator = Settings.getOperatorByIccId(iccId);
  var number = iccManager.getIccById(iccId).iccInfo.msisdn;

  var data = {};
  var l10nIdPrefix;

  if (simId){
    l10nIdPrefix = 'sim-detail-';
    data['sim'] = simId;
  } else {
    l10nIdPrefix = 'simless-detail-';
  }

  info = [operator, number].filter(function(value){
    return value;
  });

  var data = info.reduce(function(dataAcc, newArgument, index){
    dataAcc['arg' + index] = newArgument;
    return dataAcc;
  }, data);

  navigator.mozL10n.setAttributes(element.querySelector('.sim-detail'),
                                  l10nIdPrefix + (info.length - 1),
                                  data);
```

locale would be something like

```
sim-detail-0 = ...
sim-detail-1 = ...
sim-detail-2 = SIM {{sim}}, {{arg1}}, {{arg2}}
simless-detail-1 = ...
simless-detail-2 = {{arg1}}, {{arg2}}
```