Set ext net and name server in Shaker templates
Set ext net and name server in Shaker templates

It sets the shaker args to override ext net and name servers [1].

[1] https://pyshaker.readthedocs.io/en/latest/tools.html

Change-Id: I1cc6d52837e3c370db5ff59f024e96d7423be63a
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

opnfv/functest,opnfv/functest