Correcting the position of editors for a chapter of an edited book

A bug fix to properly position editor(s) within the bibliography listing for a chapter of an edited book. For further details, see: https://forums.zotero.org/discussion/29174/style-removed-university-of-south-australia-2011-harvard/
Merge pull request #568 from Luboszot/patch-1

Correcting the position of editors for a chapter of an edited book