This is a bug with images in EC2

Issue: Available flavors list (t1, m3, r3, etc) seems to be pulled for the first image attached to the compute resource, and the list doesn't update when the image is changed.

For instance - the first image I attached to the resource was a Paravirtualized Instance Store-backed linux image. This image can't provision on r-class flavors, which require HVM. So I attached an HVM image - but the flavors list doesn't change, I still can't provision r-class flavors.

Steps to replicate:
1) Create EC2 compute resource
2) Add PV EBS or Instance AMI to the compute resource
3) Observe available flavors
4) Add VM AMI to the resource
5) Observe available flavors again - see that r is still not present, no matter how you try to load the form.