Fix up security group crawler and healthcheck ready for redundant prism

 - The healthcheck now returns 503 if we are not yet ready
 - The OpenStack security group crawler no longer uses the jClouds code - much faster!
 - Add origin to each object to make filtering by origin possible
Merge pull request #9 from guardian/sh-redundancy-work

Fix up security group crawler and healthcheck ready for redundant prism