Release 2.2.0

Grocy 2.2.0 is here. It is an update to make the app behave more like the web version of Grocy.
This concerns changes to the stock view as well as shopping list.

Features:

• in stock view, now missing products are shown; this makes it easier to add them to the shopping list
• it is now possible to add a shopping list entry without a product, showing the note instead
• multiple fixes to stock behaviour and shopping list
• improved design and user interface a bit
• updated localizations

The version bump is due to API changes.