Updated openstack/openstack
Project: openstack-dev/devstack  b160640d47446bf379b3299460c4e76cb6e6c7c6
null
allow for upgrade of the precise kernel

we are getting kernel crashes in the OpenStack gate, to test
getting around this we'd like devstack to be able to upgrade
the precise kernel to the latest lts backported kernel.

default to off

Change-Id: I5d47aa8d15b1b1c0386a13b65022f6b8108c5c49