Continue provision if some nodes failed

[OpenStack Infra]

https://review.openstack.org/161491
commit f7a93309473ca7673a6593f26f80a9d4fc2bac24
Author: Łukasz Oleś <email address hidden>
Date: Sun Mar 1 08:15:47 2015 +0100

    Continue provision if some nodes failed

    Astute gets nodes allowed to fail and percentage of them
    from nailgun via provision_info in format:
    {"fault_tolerance" => [{'uids'=>['1'], 'percentage' => 10}]}

    DocImpact
    blueprint: 200-nodes-support

    Change-Id: I4b185608941063c1aa3198cf1cf4a2214b24839d