bump to 0.8.0
bump to 0.8.0

- OpenstackManager#clean_environment now cleans all private images, instances, volumes, and all containers' contents for the specified tenant.
- OpenstackManager#destroy now destroys images and instances created for the build

pivotal-cf-experimental/vm_shepherd,CiscoCloud/PCF-Metapod,CiscoCloud/PCF-Metapod,pivotal-cf-experimental/vm_shepherd