Make a separate id parameter for Job

See #28 for the background info. This allows the calling application to separate its controller from the object it's trying to update.

## WDLL

* the updated method call would look like:
``` ruby
MetadataListener::Job.perform_later(
  path: 'file_path',
  endpoint: 'http//....',
  id: 'database id for the file',
  api_token: 'xxxx'
)
```