[ADD] empty smart button place holder to easy inheritance

agreement/views/agreement.xml

@@ -30,6 +30,8 @@
                     <field name="stage_id" widget="statusbar" clickable="True" options="{'fold_field': 'fold'}"/>
                 </header>
                 <sheet>
+                    <div class="oe_button_box" name="button_box">
+                    </div>
                     <div class="oe_title">
                         <label for="name" class="oe_edit_only" string="Agreement Name"/>
                         <h1>