Add first VLAN Transparency tests

These tests are only executed if the vlan-transparent extension is installed
Advanced images are required because VLANs need to be configured on
the servers, which is not possible with cirros
Connectivity between servers via VLAN interface is verified

Functions add_route, delete_route and delete_address are added to class
IPCommand because they are needed for some VLAN Transparency downstream tests

Change-Id: I448203ead31f17a51f756667f6b3fc8e70a77ed2
4 files changed