Reorder summary columns and calculate amount from volume * avg_price

Summary now shows: Produkt | Volym (L) | Snittpris/L | Belopp
Amount is calculated as volume * average_price instead of summing transactions.

templates/customer.html

@@ -152,8 +152,8 @@
                 <tr>
                     <th>Produkt</th>
                     <th>Volym (L)</th>
-                    <th>Belopp</th>
                     <th>Snittpris/L</th>
+                    <th>Belopp</th>
                 </tr>
             </thead>
             <tbody>
@@ -161,15 +161,15 @@
                 <tr>
                     <td>{{ product.name }}</td>
                     <td>{{ product.volume }}</td>
-                    <td>{{ product.amount }} Kr</td>
                     <td>{{ product.avg_price }} Kr</td>
+                    <td>{{ product.amount }} Kr</td>
                 </tr>
                 {% endfor %}
                 <tr class="grand-total-row">
                     <td>Totalt</td>
                     <td>{{ customer.summary.total_volume }}</td>
-                    <td>{{ customer.summary.grand_total }} Kr</td>
                     <td></td>
+                    <td>{{ customer.summary.grand_total }} Kr</td>
                 </tr>
             </tbody>
         </table>