Add extra NIC to instance being created for communication
Add extra NIC to instance being created for communication

When an instance is being created, add an extra NIC (if necessary)
which is meant to be used by the instance communication.

Signed-off-by: Jose A. Lopes <0fb9c4f8511df4ec2ae28af879e9d462f6218a2c@google.com>
Reviewed-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>

yiannist/ganeti,andir/ganeti,onponomarev/ganeti,andir/ganeti,leshchevds/ganeti,leshchevds/ganeti,andir/ganeti,dimara/ganeti,ganeti/ganeti,bitemyapp/ganeti,apyrgio/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti,yiannist/ganeti,mbakke/ganeti,yiannist/ganeti,mbakke/ganeti,ganeti/ganeti,bitemyapp/ganeti,onponomarev/ganeti,grnet/snf-ganeti,ganeti/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,apyrgio/ganeti