Add translations for :taxonomies and :taxon in tabs for russian locale

Spree edge now have two additional tabs ```taxonomies``` and ```taxons```:

```erb
<% content_for :sub_menu do %>
  <ul id="sub_nav" data-hook="admin_product_sub_tabs" class="inline-menu">
    <%= tab :products, :match_path => '/products' %>
    <%= tab :option_types, :match_path => '/option_types' %>
    <%= tab :properties %>
    <%= tab :prototypes %>
    <%= tab :taxonomies %>
    <%= tab :taxons %>
  </ul>
<% end %>

I've added russian localization for them.
```