Subpages don't inherit properly space rating configuration

At this moment the ratings can be configured at space level in WebPreferences document of that space.
A.B.C.WebHome will check if in A.B.C.WebPreferences exists a XWiki.RatingsConfigClass object and if not, then jumps to XWiki.RatingsConfig document to get configuration from there.
Instead, it should look in A.B.C.WebPreferences, A.B.WebPreferences and A.WebPreferences before the fallback to XWiki.RatingsConfigdocument.