Rename Delivery.delivered_on to date

This aligns it with column names of StockTaking and us to use inheritance
in a next step to share common code between the entities.

app/views/deliveries/_form.html.haml

@@ -131,7 +131,7 @@
         = render :partial => 'stock_change_fields', :locals => {:f => stock_change_form}
 
   %h2= t '.title_finish_delivery'
-  = f.input :delivered_on, as: :date_picker
+  = f.input :date, as: :date_picker
   = f.input :note, input_html: {size: '35x4'}
   .form-actions
     = f.submit class: 'btn btn-primary'

app/views/deliveries/index.html.haml

@@ -3,13 +3,13 @@
 %table.table.table-striped
   %thead
     %tr
-      %th= heading_helper Delivery, :delivered_on
+      %th= heading_helper Delivery, :date
       %th.numeric= t 'deliveries.invoice_amount'
       %th= heading_helper Delivery, :note
   %tbody
     - for delivery in @deliveries
       %tr
-        %td=h delivery.delivered_on
+        %td=h delivery.date
         %td.numeric= link_to_invoice(delivery)
         %td= truncate delivery.note
         %td

app/views/deliveries/show.html.haml

@@ -3,8 +3,8 @@
 %dl
   %dt= heading_helper Delivery, :supplier
   %dd= @delivery.supplier.name
-  %dt= heading_helper Delivery, :delivered_on
-  %dd= @delivery.delivered_on
+  %dt= heading_helper Delivery, :date
+  %dd= @delivery.date
   %dt= t 'deliveries.invoice_amount'
   %dd= link_to_invoice(@delivery)
   - if @delivery.invoice