enabled to select the net-id of quantum when you boot the instance.

I enabled to select the net-id of quantum when you boot instances.

<http://docs.openstack.org/api/openstack-compute/2/content/CreateServers.html>

This OpenStack API Guide does not contain about booting with net-id of quantum. 
So I checked API by executing the 'nova boot --nic' command. 

and This patch also enabled to select 'v4-fixed-ip' and 'port-id'.

I did test with mock and real openstack router of folsom (2012.2.1) release.

Best regards from Tokyo. :D