Use bare config accessors

README.md

@@ -46,7 +46,7 @@ An example would be adding this to the registration page:
 
 ```erb
 <%# spree/checkout/registration.html.erb %>
-<% if Spree::Config[:allow_guest_checkout] && current_order.subscription_line_items.empty? %>
+<% if Spree::Config.allow_guest_checkout && current_order.subscription_line_items.empty? %>
 ```
 
 This allows guests to add subscriptions to their carts as guests, but forces them to login or create

app/controllers/spree/admin/installments_controller.rb

@@ -12,7 +12,7 @@ def index
 
         @installments = @search.result(distinct: true)
           .page(params[:page])
-          .per(params[:per_page] || Spree::Config[:orders_per_page])
+          .per(params[:per_page] || Spree::Config.orders_per_page)
       end
 
       private

app/controllers/spree/admin/subscriptions_controller.rb

@@ -10,7 +10,7 @@ def index
         @subscriptions = @search.result(distinct: true)
           .includes(:line_items, :user)
           .page(params[:page])
-          .per(params[:per_page] || Spree::Config[:orders_per_page])
+          .per(params[:per_page] || Spree::Config.orders_per_page)
       end
 
       def new

app/models/solidus_subscriptions/subscription.rb

@@ -386,7 +386,7 @@ def set_payment_method
     end
 
     def set_currency
-      self.currency ||= ::Spree::Config[:currency]
+      self.currency ||= ::Spree::Config.currency
     end
 
     def generate_guest_token