Add tunnel_name and tunnel_vm_name variable to NetworkGroupTunnel

[fabricekrebs]

When creating a NetworkGroupTunnel, the name of the TunnelVM shown on Calm is the name of the class, and the name of the tunnel need to be manually specified, with the command (calm create network-group-tunnel -f project_definition.py -n name-of-you-vm).

NetworkGroupTunnel class should be improved to allow the 2 following variables :

• Being able to specify the Tunnel Name within the NetworkGroupTunnel class to avoid to be force to specify it with the -n parameter
• Being able to specify the, instead of Tunnel VM Name taking the className and just append VM at the end.

Suggested improvement :

• Add tunnel_name variable to NetworkGroupTunnel to specify the Calm Tunnel Name
• Add tunnel_vm_name variable to NetworkGroupTunnel to specify the Calm Tunnel VM Name