- add validation to prevent direct creation / deletion (if using people container)
- should fix other possible inconsistencies with personCache
- add unit tests
- minor cleanup
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@23038 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261