Don't assume nova-manage is present
Don't assume nova-manage is present

tools/discover_hosts.sh is run by devstack-gate, and breaks all dsvm job
that doesn't use nova.

nova-manage is perhaps not installed if nova services are not enabled.

This change checks the presence of nova-.

Change-Id: Ic555d241f98d0fa027897c69a7115d1be88f6c96

openstack-dev/devstack,dtroyer/devstack,noironetworks/devstack,noironetworks/devstack,richliu/devstack,nawawi/openstack,nawawi/openstack,richliu/devstack,group-policy/devstack,group-policy/devstack,dtroyer/devstack,openstack-dev/devstack