Add arm64 support for grafana

[Jorge Niedbalski]

[Description]

The current docker file returns the following message
on aarch64.

{% if base_arch != 'x86_64' %}

RUN echo 'There are no Grafana external repositories for {{ base_arch }}' \
    && /bin/false

{% endif %}

Grafana upstream is currently working to produce ARM releases via
https://github.com/grafana/grafana-docker/issues/117 , this is work in progress
and part of their new CI/CD pipeline.

There is still a non-official repository for arm packages on bintray that
can be found here https://github.com/fg2it/grafana-on-raspberry/wiki#with-apt-from-bintray-debian-repository

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/565863
Committed: https://git.openstack.org/cgit/openstack/kolla/commit/?id=bfa0fe778f2d4305f3ba9017db162af835335fdc
Submitter: Zuul
Branch: master

commit bfa0fe778f2d4305f3ba9017db162af835335fdc
Author: Jorge Niedbalski <email address hidden>
Date: Wed May 2 15:18:06 2018 -0300

    Add Grafana repository for arm64

    Official ARM support as part of the release process of grafana is on
    development [0].

    For now, the closest official repositories are the ones from fg2it
    repository, which is also part of the developers working on the support,
    so we are adding it to the sources for now until the official support is
    done.

    [0] https://github.com/grafana/grafana-docker/issues/117

    Bug: #1768585

    Signed-off-by: Jorge Niedbalski <email address hidden>

    Change-Id: Iba004f99c0ac92cb660e405c5ac9c61dc7fa81e2

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.openstack.org/566697

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/566697
Committed: https://git.openstack.org/cgit/openstack/kolla/commit/?id=48921205a5d69e26942b6b41ce1a0fbe88a4d7b3
Submitter: Zuul
Branch: stable/queens

commit 48921205a5d69e26942b6b41ce1a0fbe88a4d7b3
Author: Jorge Niedbalski <email address hidden>
Date: Wed May 2 15:18:06 2018 -0300

    Add Grafana repository for arm64

    Official ARM support as part of the release process of grafana is on
    development [0].

    For now, the closest official repositories are the ones from fg2it
    repository, which is also part of the developers working on the support,
    so we are adding it to the sources for now until the official support is
    done.

    [0] https://github.com/grafana/grafana-docker/issues/117

    Bug: #1768585

    Signed-off-by: Jorge Niedbalski <email address hidden>

    Change-Id: Iba004f99c0ac92cb660e405c5ac9c61dc7fa81e2
    (cherry picked from commit bfa0fe778f2d4305f3ba9017db162af835335fdc)