Refactoring. Moved shared code into separate functions.
Added edit action for DNS module's CLI mode. Hostname editing supported.
Updated changelog.

Conflicts:

	VERSION
	package/yast2-network.changes

Conflicts:

	VERSION
	package/yast2-network.changes
Refactoring DNS. Added setters which are mainly used by CLI.
DNS CLI supports editing nameservers.
Updated changelog.

Tested manually on SLE11-SP3-Alpha42, with
/sbin/yast2 dns edit hostname=su-se nameserver1=1.2.3.4
Merge pull request #48 from mchf/Code-11-SP3

Agreed by mvidner before editing commit message for commit 6c6aaea