engine: Adjust SetupNetworks to accept any vlan device name

Changes done in this patch-
1. SetupNetworks uses iface.getBaseInterface() and iface.getVlanId()
instead of determining this values from the vlan device name (since its
format is no longer- baseIface.vlanId).
2. SetupNetworks uses the new methods indroduced in NetworkUtils instead of
the old ones (that should be removed in a following patch).

Change-Id: Ic08c952a7c1902d176709af7126f54ab37a0344d
Bug-Url: https://bugzilla.redhat.com/1091863
Bug-Url: https://bugzilla.redhat.com/999975
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>