Changeset:

- Charge model added.
- Charge serialization test suite added.
Changeset:

- Charge model added.
- Charge serialization test suite added.
Charge model updated.
Charge details refactoried to another compile unit.
Changeset:

- Modificaciones en los modelos.
- Pruebas actualiadas.
Charge refund added.
Changeset:

- Charge model finished.
- Charge test set updated.
- Error model created.
- Error handling in requestor added.
Merge remote-tracking branch 'origin/develop'