array check to ensure getRemoteJoinField() gets an array from Config::inst()->get($remoteClass, 'has_one') (related issue: #2570)
API: DataObject->getRemoteJoinField() no longer defaults to ParentID but throws an exception instead
Merge pull request #2572 from Zauberfisch/api-getRemoteJoinField-enhancement-2570

API: DataObject->getRemoteJoinField() no longer defaults to ParentID but throws an exception instead