engine: Adjust NetworkUtils to accept any vlan device name - phase 2

This patch contains-
1. Removing from all the old methods assuming vlan device name format is
baseNic.vlanId from NetworkUtils.
2. Fixing NetworkUtilsTest.

The patch is the last one in a chain of patches.
The previous patches fixed all the places thats used the old methods.

Change-Id: I884ea51d4c7b47fef2b7fb2c89b4efd36701980c
Bug-Url: https://bugzilla.redhat.com/1091863
Bug-Url: https://bugzilla.redhat.com/999975
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>