Updated openstack/openstack
Project: openstack-dev/devstack  8e087fa83b1a1b1a2cdbae6f855c9d742e5650f5

XenAPI: Upgrade built-VM to Trusty

If you're not using an XVA then the built-VM was previously Saucy, which is
not supported by openstack any more.

Change-Id: I1040d9e43d517582e76f2e1df787986b5ffbc42c