Attach persistent disk before deleting vm when recreating the vm

Signed-off-by: Phan Le <ple@pivotal.io>
Convert to new rspec syntax

Signed-off-by: Phan Le <ple@pivotal.io>
Move shared code for vm recreation test into external function

Signed-off-by: Phan Le <ple@pivotal.io>
Add integration test for recreating VMs with dead agents

Signed-off-by: Phan Le <ple@pivotal.io>