Remove confusing show_descendants configuration. Fixes #3212
Placeholders translation, 'None' translation in selectors, shipment_states translations

Fixes #3271
Logs exception message & backtrace to rails log [Fixes #3290]
Scope eligible when choosing best adjustment

When the order had a better but not eligible adjustment the store would
make all other adjustments not eligible. Instead it should scope
eligible adjustments when figuring out which one should make it to the
order

thanks to @sohara for pointing that out

Fixes #3274