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"
  ]
}
```
This is good for edxapp but won't work for celery workers which aren't run under gunicorn.  What's the right thing to do, add a second voter for celery?