[FIX] mail,website_forum: set SELF_WRITABLE_FIELDS on model's class

Otherwise it is not visible when set on an instance of the new API.
self is a recordset instead of the model `res.users`

Without this patch a low priviledge user was not able to modify its own value
of `notify_email` through the preference window.

addons/mail/models/res_users.py

@@ -27,11 +27,11 @@ class Users(models.Model):
         """
         init_res = super(Users, self).__init__(pool, cr)
         # duplicate list to avoid modifying the original reference
-        self.SELF_WRITEABLE_FIELDS = list(self.SELF_WRITEABLE_FIELDS)
-        self.SELF_WRITEABLE_FIELDS.extend(['notify_email'])
+        type(self).SELF_WRITEABLE_FIELDS = list(self.SELF_WRITEABLE_FIELDS)
+        type(self).SELF_WRITEABLE_FIELDS.extend(['notify_email'])
         # duplicate list to avoid modifying the original reference
-        self.SELF_READABLE_FIELDS = list(self.SELF_READABLE_FIELDS)
-        self.SELF_READABLE_FIELDS.extend(['notify_email', 'alias_domain', 'alias_name'])
+        type(self).SELF_READABLE_FIELDS = list(self.SELF_READABLE_FIELDS)
+        type(self).SELF_READABLE_FIELDS.extend(['notify_email', 'alias_domain', 'alias_name'])
         return init_res
 
     def get_alias_model_name(self, vals):

addons/website_forum/models/res_users.py

@@ -12,7 +12,7 @@ class Users(models.Model):
 
     def __init__(self, pool, cr):
         init_res = super(Users, self).__init__(pool, cr)
-        self.SELF_WRITEABLE_FIELDS = list(
+        type(self).SELF_WRITEABLE_FIELDS = list(
             set(
                 self.SELF_WRITEABLE_FIELDS +
                 ['country_id', 'city', 'website', 'website_description', 'website_published']))