initial working version

@feanil @jarv  Inventory script targeting the ASG.  Could be rolled into ec2.py, but I'd rather get our version to the latest and fix it to use profiles before integrating.

Output looks like so:
```
{
  "InService": [
    "10.0.47.127", 
    "10.0.30.137"
  ], 
  "Terminating:Wait": [
    "10.0.11.83"
  ], 
  "e-d-CommonClusterServerAsGroup": [
    "10.0.47.127", 
    "10.0.46.174", 
    "10.0.48.104"
  ], 
  "e-d-CommonClusterServerAsGroup_InService": [
    "10.0.47.127", 
    "10.0.46.174", 
    "10.0.48.104"
  ]
}
```
what is `add_argument_group` used for here?