Revert "Use default Person's site & group as set by respective Career settings (not any more Person's Assignments)."

This reverts commit 9e37696077cf7fd0547b73494b190da2eb44bd7e.
Afterall, it seems more logical to use assignments because security depends on
assignements, so a user with inconsistent careers definition could create a
document that he cannot view/modify
Revert "Meta data discovery uses subordination through Career rather than Assignments."

This reverts commit 96bfc618e48815bf1bc24cab8bdeccc64467992b.
make diff even if not xml
BT: fix diff for ZODB components