Render shipping cost nanos in emailservice

The template used for the confirmation email in the emailservice did not
render the nanos of the shipping cost. This commit adds them, so the
rendering of shipping cost and item cost (lower in the template) is
equivalent.

src/emailservice/views/confirmation.erb

@@ -32,7 +32,7 @@
     <p><%= order.order_id %></p>
     <h3>Shipping</h3>
     <p><%= order.shipping_tracking_id %></p>
-    <p><%= order.shipping_cost.units %>.<%= order.shipping_cost %> <%= order.shipping_cost.currency_code %></p>
+    <p><%= order.shipping_cost.units %>.<%= order.shipping_cost.nanos %> <%= order.shipping_cost.currency_code %></p>
     <p><%= order.shipping_address.street_address_1 %>, <%= order.shipping_address.street_address_2 %>, <%= order.shipping_address.city %>, <%= order.shipping_address.country %> <%= order.shipping_address.zip_code %></p>
     <h3>Items</h3>
     <table style="width:100%">