[REM] sale: Remove unused less rule

addons/sale/static/src/less/sale.less

-.openerp .oe_margin_top_4 {
-	margin-top: 4px;
-}

addons/sale/views/sale_templates.xml

@@ -3,7 +3,6 @@
         <!-- inherits from sales_team.assets_backend to override certain attributes defined in sales_team -->
         <template id="assets_backend" name="project assets" inherit_id="sales_team.assets_backend">
             <xpath expr="." position="inside">
-                <link rel="stylesheet" href="/sale/static/src/less/sale.less" type="text/less"/>
                 <script type="text/javascript" src="/sale/static/src/js/sale.js"></script>
             </xpath>
         </template>