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
It's not a $zone. It's a number (Integer offset) pointing to a zone data in the array of zones. $z is used in different context in the same code - that would IMO cause confusion.