Fix EZP-20539: Public API - Defaut editor permissions not working correctly

This is 2nd approach to fixing application of subtree limitations when Content has no Locations. Currently this presents a problem when publishing first drafts with Legacy Storage engine.

A new method ```loadParentLocationsByContent``` is added to Location handler, so that subtree limitation can be applied against parent locations of a content.

For some more info see https://jira.ez.no/browse/EZP-20539#comment-73063