clarify failure of nova-compute
clarify failure of nova-compute

The VM provisioning process involves many components - not just
nova-compute, but also libvirtd, and services on other nodes (keystone,
glance etc.).  So be more specific here and simply talk about
nova-compute.

Also, nova-compute being down is a state not an event, and it's not
necessarily even a failure state, since it could have been shut down
deliberately.  So change this to two examples of genuine failure events:
crashing and becoming unresponsive.

Change-Id: Icb63a718edfb64eef3c1bdeb3252c29b2dadad80
Signed-off-by: Adam Spiers <a3b1ac66d44425905084924ee6cef90b31d2e761@suse.com>

openstack/openstack-user-stories