Create cloud server images

This change adds a cloud-image/create_image.py script that will create a server image in your Rackspace account.

cd cloud-image
python create_image.py

It will prompt you for rackspace credentials to use.  These options can also be passed in on the command line.  The script takes about 15 minutes to complete.

Right now the script uses Fabric, which means it is Python 2 only.  After cleaning up there is only one ssh call remaining, so we could move away from Fabric and use Python 3 without too much work.