[8.0] late artifacts cannot be built with new kernel

[Denis Meltsaykin]

fuel-main is hardcoded to use a specific CentOS snapshot (7.1.1503) and linux-kernel only from the "os" repository. This causes failures during building "late artifacts" if a new kernel is present in a non-"OS" repository.

Actual result:
https://packaging-ci.infra.mirantis.net/view/All/job/8.0-build.late.artifacts/59/console

find /home/jenkins/workspace/tmp/8.0-build.late.artifacts/local_mirror/centos/os/x86_64 -name 'kernel-3.10.0*' | xargs rpm2cpio | \
  (cd /home/jenkins/workspace/tmp/8.0-build.late.artifacts/build/bootstrap/; cpio -imd './boot/vmlinuz*')
argument is not an RPM package
cpio: premature end of archive

Expected result:
Late artifacts are built with a new kernel from any repository available.

[Denis Meltsaykin (dmeltsaykin)]

Review: https://review.openstack.org/#/c/365613/
Late artifacts are built successfully: https://packaging-ci.infra.mirantis.net/view/All/job/8.0-build.late.artifacts/63/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/365613
Committed: https://git.openstack.org/cgit/openstack/fuel-main/commit/?id=7c80bb29ce1062e60285d53e4c5ff8a082c005f2
Submitter: Jenkins
Branch: stable/8.0

commit 7c80bb29ce1062e60285d53e4c5ff8a082c005f2
Author: Denis V. Meltsaykin <email address hidden>
Date: Mon Sep 5 15:23:53 2016 +0300

    Fix kernel installation into bootstrap image

    The commit changes paths where kernel packages are being found during
    building of the bootstrap image. This allows to use any repository with
    an updated kernel package instead of the previously hardcoded
    os-repository.

    Change-Id: Ib927dd99c18196559fd81a30f7dc23b8f6fa2b6e
    Closes-Bug: #1620284