engine: Adjust NetworkMonitoringHelper to accept any vlan device name

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

Change-Id: I96c998b8575bc8d48ec482d725de3579f51a7c88
Bug-Url: https://bugzilla.redhat.com/1091863
Bug-Url: https://bugzilla.redhat.com/999975
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>