[hp|compute_v2] added security group support

This PR adds security groups to the compute_v2 services for the HP. A lot of this code was re-used from the compute service.

@rupack Do you want to give this a quick glance?

@geemus I also noticed that out of the 3 providers that support security groups (aws, hp, and openstack) all three of have a slightly different interface. I added `SecurityGroup#authorize_port_range` to match the aws interface, but I wonder if we should take the time to define a common interface for SecurityGroups. I am leaning towards the OpenStack implementation as it has a much more OO interface. Thoughts?