Consistent error handling

- [x] Server must return errors that have consistent format.
- [x] Unify way of handling with Throw and Callback errors.
- [x] Handle all errors. Now app can skip some errors, for example in PulsarDB.
Hm, but tests require pulsar.config.repo. Please see https://github.com/cargomedia/pulsar-rest-api/blob/9933bae750524eafa5fab2075ceb4cc56c11f064/test/pulsar.js#L46