VLAN Test

[bytinbit]

Add Basic TestCase for VLANs via Napalm.
Checks if:

• Do the Switches have the VLANS which they are supposed to have (and nothing else)?
• Trunk: Are only the VLANS allowed which are supposed to be allowed?

[bytinbit]

implemented here: https://github.com/marcom4rtinez/nuts/tree/1-test-bundle-prototyp-vlan-test

[lucmurer]

Done by @marcom4tinez and @sevigrimm for Release 3.1.0