EC2 VPC network interface run, group, and attribute updates - EUCA-9609

More network interface parameters are now supported when running a vpc
instance. An existing network interface can now be used when running a
single instance and network interface security groups are used.

Network interfaces now have security group support with create, describe
and modify attribute actions.

EUCA-9609
EC2 VPC subnet available address tracking - EUCA-9786

Allocated private addresses are now tagged with the subnet they belong
to. On allocation / release of a tagged address we refresh the available
address count for the corresponding subnet.

EUCA-9786
Merge remote-tracking branch 'origin/dev/sjones/EUCA-9786' into testing