VLANs cannot be added to bond

see https://bugzilla.novell.com/show_bug.cgi?id=790219#c22
added changes
VLAN ID validation - accept only integers in range 0..4094
atheros physical devices have athX device name
bond interface requires at least one slave
verify unique VLAN ID
updated changes

- 0.3.15
use begins_with?
Merge pull request #81 from webyast/network_fixes

Network - added checks to avoid invalid configurations