Additional fixes to make CS12 and loadtesting work

* VIP assignment now works correctly in CS12
* Fix user creation so that all users are admins
* Set a sane default for analytics topology
* Fix knife-container installation on loadtester_host
* Make it possible to use a different AMI type, subnet, ssh_username for each machine within it's config definition like:
```json
     "loadtester_spec": {
        "hostname": "loadtester1.rhel.aws",
        "ebs_optimized": true,
        "instance_type": "m3.2xlarge",
        "ssh_username": "ubuntu",
        "ami_id": "ami-3d50120d"
      }
```