[r=axwalk] environs/manual: use old AddMAchines API
[r=axwalk] environs/manual: use old AddMAchines API

Manual provisioning was implicitly changed
to use the new AddMachinesV2 client API,
with no backwards compatibility failover.
I've changed it to explicitly use the old
API, since we do not require anything of
the new one.

Fixes lp:1317267

https://codereview.appspot.com/95150043/
reedobrien/store