add correct message for equipping equipment

Currently, when you put on equipment, you see the messageBought notification. There was no messageEquipped notification in the code so I've added one.

I've updated ALL locale files IN ENGLISH, following the convention already in place for using English when there is no translation (e.g., locales/pl/messages.json, locales/sv/messages.json).
Merge pull request #219 from Alys/messageEquipped

add correct message for equipping equipment