Modify LUInstanceSetParams() to support networks

Keep backwards compatibility just like LUInstanceCreate() and support
network parameter for NIC object.

Add ec_id argument in Update() to be able to commit temporary IPs that
were previously reserved.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Reviewed-by: Iustin Pop <iustin@google.com>