[FIX] website_sale: multi-image, fix group assignation in res_config

Old code introduced an error, because every body was public user and
so the menu e.g. login appears even when you was logged in.

Courtesy of @kangol

addons/website_sale/models/res_config.py

@@ -15,4 +15,4 @@ class WebsiteConfigSettings(models.TransientModel):
     module_delivery_ups = fields.Boolean("UPS integration")
     module_delivery_usps = fields.Boolean("USPS integration")
     module_sale_ebay = fields.Boolean("eBay connector")
-    group_website_multiimage = fields.Boolean('Multi Image', implied_group='website_sale.group_website_multi_image')
+    group_website_multiimage = fields.Boolean('Multi Image', implied_group='website_sale.group_website_multi_image', group='base.group_portal,base.group_user,base.group_public')

addons/website_sale/security/website_sale.xml

@@ -39,7 +39,6 @@
     <record id="website_sale.group_website_multi_image" model="res.groups">
         <field name="name">Show multi image on eCommerce</field>
         <field name="category_id" ref="base.module_category_hidden"/>
-        <field name="implied_ids" eval="[(6,0,[ref('base.group_portal'), ref('base.group_user'), ref('base.group_public')])]"/>
     </record>