Additives now displayed per categories (issue #24)

By default E100-199 additives range is displayed. Users may click on the additive category tabs and select another range.
Adapted searching of additives in separate partial.

This change is required due to issue #24.
Fixes in displaying items on additives page

Add: Category name is now displayed in breadcrumbs.
Fix: Active and Inactive tabs now have different styles.