compute: notify nova-compute on set_secret_value_virsh refreshing

When running set_secret_value_virsh, we have to notify nova-compute
service, otherwise nova will fail to connect to RADOS.

Partial-bug #582
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Merge pull request #585 from enovance/bug/582/emilienm

compute: notify nova-compute on set_secret_value_virsh refreshing