Uses the taxonomy method in the show taxonomy API action.

So it is easier to extend it.
Extracts taxonomies scope to its own method in the taxonomies controller.

So it is easier to extend it.
Added Korean translations for JQuery validate plugin

Fixes #4740
explained tests dependency how to set up environment

Fixes #4705
Fall back to name on CreditCard#to_active_merchant

Gateway provided via active merchant might use those first and last name
instead of the single name string

Fixes #4728