销售订单添加合同字段，销售订单form页面新增合同page页，优化/api/bfm_process_order/list接口添加合同信息处理。

sf_sale/views/sale_order_view.xml

@@ -198,7 +198,20 @@
                     </div>
                     <field name="date_order" attrs="{'invisible': [('state', 'in', ['done', 'cancel'])], 'required': True}" nolabel="1"/>
                 </xpath>
-
+                <xpath expr="//notebook/page[@name='customer_signature']" position="after">
+                    <page string="合同" name="contract_documents"
+                          attrs="{'invisible': [('contract_document_id', '=', False)]}">
+                        <group>
+                            <group>
+                                <field name="contract_document_id" invisible="1"/>
+                                <field name="contract_file_name" invisible="1"/>
+                                <field name="contract_file"
+                                       widget="adaptive_viewer"
+                                       filename="contract_file_name"/>
+                            </group>
+                        </group>
+                    </page>
+                </xpath>
             </field>
         </record>