Rename translation key checkout to avoid conflicts

A top-level translation key `checkout` can't co-exist with translation
keys in the path `checkout`. Moving the old key to
`shared.menu.cart.checkout` avoids conflicts. It also structures the
locale better by view.

app/views/shared/menu/_cart.html.haml

@@ -15,7 +15,7 @@
         %a.button.secondary.tiny.add_to_cart{ href: cart_path, type: :submit, "ng-disabled" => "Cart.dirty || Cart.empty()", "ng-class" => "{ dirty: Cart.dirty }" }
           = "{{ Cart.dirty ? '#{t(:cart_updating)}' : (Cart.empty() ? '#{t(:cart_empty)}' : '#{t(:cart_edit)}' ) }}"
         %a.button.primary.tiny{href: checkout_path, "ng-disabled" => "Cart.dirty || Cart.empty()"}
-          = t 'checkout'
+          = t '.checkout'
       %table
         %tr.product-cart{"ng-repeat" => "line_item in Cart.line_items", "id" => "cart-variant-{{ line_item.variant.id }}"}
           %td
@@ -47,7 +47,7 @@
         %a.button.secondary.tiny.add_to_cart{ href: cart_path, type: :submit, "ng-disabled" => "Cart.dirty || Cart.empty()", "ng-class" => "{ dirty: Cart.dirty }" }
           = "{{ Cart.dirty ? '#{t(:cart_updating)}' : (Cart.empty() ? '#{t(:cart_empty)}' : '#{t(:cart_edit)}' ) }}"
         %a.button.primary.tiny{href: checkout_path, "ng-disabled" => "Cart.dirty || Cart.empty()"}
-          = t 'checkout'
+          = t '.checkout'
       - if show_bought_items?
         %h5{"ng-if" => "Cart.line_items_finalised.length", style: 'margin-top: 1em'}
           = t '.already_ordered_products'

config/locales/en.yml

@@ -558,6 +558,7 @@ en:
   shared:
     menu:
       cart:
+        checkout: "Checkout now"
         already_ordered_products: "Already ordered in this order cycle"
     register_call:
       selling_on_ofn: "Interested in getting on the Open Food Network?"
@@ -656,7 +657,6 @@ en:
   items: "items"
   cart_headline: "Your shopping cart"
   total: "Total"
-  checkout: "Checkout now"
   cart_updating: "Updating cart..."
   cart_empty: "Cart empty"
   cart_edit: "Edit your cart"