Releasenotes V0.9.0

Main Features
- Added support for sub items
- Added support for total discounts

TrustedFiscalModule 
- Added support for subitems (item sets) in document model
- Marked DocumentPayment.IsCash as german fiscalisation required, better documentation for this class
- Added method to get vat identification for vat percentage and date/time 
- Added RowType RowTotal (DocumentPositionTotal) to setup total discounts, must be last position in position collection
- Added support for quantityunit's

TrustedFiscalService
- Improved logging of fiscal service
- Added Schema for DocumentPositionTotal in swagger notation
- Added method getVatIdentifcation [Route("client/{clientId}/getVatIdentification"), HttpGet] to InformationController
- Corrected return result of management controller getClient [Route("clients/get/{clientId}"), HttpGet]
- Improved documentation of management controller
- Improved documentation of transaction controller (Exceptions)
- Improved asp.net middleware to serve better response codes (+HttpStatusCode.NotImplemented (501))
- Added method ValidateClient to management controller

FiscalServiceClient.net2
- Added DocumentPositionTotal to document model
- Bugfix: FiscalResponse crashes with additional information

FiscalServiceClient
- Bugfix: FiscalResponse crashes with additional information