[IMP] res.partner: more selective child_of _search() hack

Makes the conditions for disabling the `active` test
on res.partner.search() more selective, to avoid
triggering it when we are not actually searching for
the children of specific parents.
(Broke base tests now that data includes an deactivated
partner)
[REVERT] revert commit 5210 chs@openerp.com-20140130150628-qqbno0nu8mp27b9u: bring back magic
[FIX] allow "none" route to be accessible when logged in