Fix for improper Notify info parsing

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Fix empty field in case of a very first Offer/Update command

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Use proto_item_append_text instead of rewriting the entire item's text

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>