Feature: make Beans customizable, like brewing parameters

[silasg]

After adding the processing to Beans (see #98) there are other ideas for new fields: Region, Height/MASL, Cupping Score, Farm, Harvest, Bean Pattern (? "Bohnenbild") and maybe even more.

If those are added, a feature to show/hide certain fields when creating, updating and showing bean details would be needed. Maybe one also wants to change the order of fields (I personally would not need this).