enabling 'private_ip_address' so ec2.py can find hosts in the VPC

This presumes that we have some way to actually *get* to hosts in the VPC.  We still need to figure that out -- could be DNS with some fancy routing, could be a statically generated/distributed ssh config file. But we have to still do ssh forwarding through the Bastion to get to these machines, even if ec2.py will now list them.

I'll do separate tooling for that next, probably in the same branch.