Fixing missing translations in Spree v2

Fixes #227
Correct Zip to Post Code and State to County for en-GB

Fixes #229
Update ja.yml

InventoryUnit#state doesn't mean 'prefecture'(県).

Fixes #230
Move Czech locale from cs-CZ.yml to just cs.yml
Merge branch 'master' into develop

Conflicts:
	config/locales/cs.yml
	config/locales/en-GB.yml