Used to access directly to VM.

In case of erp5testnode, we have only one IP. So slapos node instance on clone instance would reach... slapproxy of main slaprunner.

slaprunner: resiliency: allow jinja to read slapparameter_dict and to bubble intsance parameters to main instance.

Obvious effect: don't consider processes like mysql as running if it comes from another partition (case of erp5testnode).
Less obvious effect: don't sync/delete supervisord.sock.
Less obvious effect: in erp5testnode, don't uninstall things from main instace when running buildout of instance of clone runner instance.

A new parameter 'use-nat', True by default will specify if we will setup a nat interface.
if 'use-tap' is Truei (false by default), a tap interface will be connected with a new interface in kvm.
if 'use-tap' and 'use-nat' are True, then virtual machine will have two interfaces, one with tap and
one with nat.