Don't crash if VM has invalid disks

Useful if storage=False and removing a VM.

client-common/vm.py

@@ -261,10 +261,13 @@ def remove_vm(zk_conn, domain, is_cli=False):
     # Remove disks
     for disk in disk_list:
         # vmpool/vmname_volume
+        try:
             disk_pool, disk_name = disk.split('/')
             retcode, message = ceph.remove_volume(zk_conn, disk_pool, disk_name)
             if is_cli and message:
                 click.echo('{}'.format(message))
+        except ValueError:
+            continue
 
     return True, 'Removed VM "{}" and disks from the cluster.'.format(domain)