Updated openstack/openstack
Project: openstack/ceilometer  ae828f2686bd522d3271e2d51791eda70bcd825d

switch to sqlalchemy core

ORM has an overhead associated with it. we need fast writes so
switch to use sqlalchemy core to improve performance.

Closes-Bug: #1356000
Change-Id: I45c76d4f294f9bdb6d0f04e94d4be7e0f7ca6f2a