Added functionality for checking network (w/o netmask)

- Added mostly for IPv6 support bnc#800592
New version and changes file entry
separation of netmask and prefix validation in Netmask module

svn path=/trunk/yast2/; revision=58786

Conflicts:
	VERSION
	package/yast2.changes
Added missing changes file entry from the cherry-picked change
Readded SP3 functionality for backward compatibility
Merge pull request #63 from kobliha/Code-11-SP3

Added functionality for checking network entry with optional netmask in IP or CIDR format (bnc#800592).

The last commit (48997e6) is because yast2-network depends on the old semantic. In master it was fixed by changing the user code:
https://github.com/yast/yast-network/commit/ade6b50428aba00fc2524adac85d1e3438b6717e