use interactive option during the deletion of volumes, snapshots and backups

Use the interactive option with delete volumes/snapshots/backups. Similar to (linux command "rm -i"). For ex:
% cinder delete <vol-id> interactive
Do you rellay want to delete the <vol-id>? y/n:

if y -> delete the volume else cancel the operation.

Details:

- prompt before every removal of volumes/snapshots/backups using 'delete' command.