Release v2.1 of Abacre Restaurant Server

* Feature: implemented Worker hours report.
* Feature: implemented Report filter on Orders page to show all orders or open orders.
* Improvement: after adding item to order item's category is shown instead of order window.
* Feature: added Kitchen/Bar view.
* Feature: added Year-Month parameter into sales by period report.
* Feature: added reports page with list of reports.
* Feature: added report: Sales of Item by Period.
* Feature: added Notes field on vendor Order page.
* Feature: now it's possible to sort list of orders on vendor Orders page by clicking on a column name.
* Improvement: on Orders window Delete Order button is only visible to
workers with Show Delete Order button security role.
* Bug fixed: on main window server URL left to View in Browser button
was not updated automatically when changing Server Name field.