Fixes #60 (app) : add alias to user schema, set alias field if doesnt exist

Yang dicek 1 baris saja pak:
```
try {
   payload = JSON.parse(job.payload.toString());
} catch (e) {
   console.log("Bogus JSON");
}

if (payload == null) {
   // payload is bogus or none
   return job.workComplete(JSON.stringify({result: false, error: err}));
}

if (payload.data && payoad.data.source && payload.data.alias) {
  ...
} else if (!payload.data.source) {
  ...
}
```