two chroot related fixes

- Pass SCR root path to stdio agents [bnc#879365](https://bugzilla.novell.com/show_bug.cgi?id=879365).
- If aborting on a SCRAgent::targetPath assertion, log it [bnc#891053](https://bugzilla.novell.com/show_bug.cgi?id=891053)

what is reason to remove it? we are in RC phase, so I would like to avoid useless changes and if you do such change, then we should really clean all places that use it.