network-vlans: Use ip link command instead of vconfig.

This patch gets rid of using vconfig for configuring VLAN
devices. ip link is much more suitable for that and creates
the interface with the right name and MAC address in just
one step.
network-vlans: Remove " from configuration values.

" is an invalid character.
vim: Update to 7.4.
Merge branch 'fifteen' of ssh://git.ipfire.org/pub/git/ipfire-2.x into fifteen