Fixed AutoYast Import() and Write()

- bnc#898659
- Imported zones were not written to the system as they were not marked as 'modified'
- Directory /etc/named.d/ was used even if it didn't exist
- The whole named.conf was rewritten from scratch as Yast thought that something has changed that file while Yast was running
Ah, sorry, it reminded me of the swp files that not-emacs creates.