Update to d2to1 0.2.10.

We fixed a string bug upstream which was released, and also added some
additional backwards_compat options.

Change-Id: I636a47952a90e6e0df864dbdc9243b77eeb6d77e
Reviewed-on: https://review.openstack.org/26968
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins