MbCashStore Added access restriction to change the sale price. Added the ability to advertise in sales receipts APK

A simple and effective application for accounting for retail sales and control of balances.
Our features:
- Intuitive interface.
- Мaintenance of directories of categories, products, customers and users.
- Support purchase documents, sales and write-offs.
- Accounting of documents with the possibility of printing and sending them by e-mail.
- Connection with ATOL cash register and print checks.
- Discount management.
- Use barcodes to manage and search products.
- Various reports (such as products turnover by date, sales\purchases history by date and etc.).
- Reports can be sent by email or can be exported in *.CSV format.
- User Account Management and trade shifts management.
- Simple import and export allow to transport and use application on different devices and make backups freely.