EUCA-8644: ImagingService instance preparation. There's a chain of steps that include:
  -- create security group
  -- create role and instance profiles
  -- create launch config and autoscaling group
  -- create server certificate
  -- authorize the role access to server certificate

To enable imaging-service, property 'imaging.imaging_service_enabled' should be set to true,
in addition to emi being set for 'imaging.imaging_emi'.
Merge branch 'dev/spark/imaging-service-merge' into testing