user_extra_sello_imagen/user_extra_sello_view.xml

<?xml version="1.0"?>
<openerp>
    <data>
        <record model="ir.ui.view" id="res_users_firma">
            <field name="name">res.users.firma</field>
            <field name="model">res.users</field>
            <field name="inherit_id" ref="base.view_users_form"/>
            <field name="arch" type="xml">
                <field name="active" position="before">
                    <field name="image" widget="image" class="oe_avatar"/>
                </field>
            </field>
        </record>

    </data>
</openerp>