Update Ukrainian translation

Fix incorrectly translated terms:

* taxon: "таксон" (literally taxon) instead of "категорія"
  (category);
* taxonomy: "таксономія" (literally) instead of "розділ"
  (section)

Add and translate strings from en.yml of spree's master branch.

Remove unused strings.
Enhance Ukrainian translation
Remove confusion about taxons in Ukrainian translation
Ukrainian: translate 'name' as 'Назва', not 'Найменування'
Merge pull request #455 from hnatt/master

Update Ukrainian translation