Cinder: Make image conversion dir an emptydir

This PS makes the image conversion directory an emptydir, so that
we can use read only containers and sill convert images from glance
into volumes.

Change-Id: Id3cda737895451c2261bf9adfe54995db28c2f63
Signed-off-by: Pete Birley <pete@port.direct>

cinder/templates/deployment-volume.yaml

@@ -138,6 +138,8 @@ spec:
               readOnly: true
             - name: pod-shared
               mountPath: /tmp/pod-shared
+            - name: cinder-conversion
+              mountPath: /var/lib/cinder/conversion
             - name: cinder-etc
               mountPath: /etc/cinder/cinder.conf
               subPath: cinder.conf
@@ -210,6 +212,8 @@ spec:
           emptyDir: {}
         - name: pod-shared
           emptyDir: {}
+        - name: cinder-conversion
+          emptyDir: {}
         - name: ceph-etc
           configMap:
             name: {{ .Values.ceph_client.configmap }}