Exclude Elasticsearch from fuel-stats reports data flow

[Alexander Kislitsky]

When fuel-stats was designed we assumed, that web UI will be used for showing differing analytic reports and charts. But now only CSV reports are used for analysis. Web UI shows only few charts with common information. Thus we don't use Elasticsearch as it was planned. Thus Elasticsearch should be removed from the fuel-stats servers. Instead it we can use cached data from the production DB with information required for charts in the web UI.

The benefits of removing Elasticsearch - saving hardware resources, simplification of fuel-stats service, removing migrator code from the fuel-stats.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/334513

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/334513
Committed: https://git.openstack.org/cgit/openstack/fuel-stats/commit/?id=8e162192493c53fce3ab30ecff7f598f8d7e883e
Submitter: Jenkins
Branch: master

commit 8e162192493c53fce3ab30ecff7f598f8d7e883e
Author: Alexander Kislitsky <email address hidden>
Date: Mon Jun 27 17:26:50 2016 +0300

    Elasticsearch removing from fuel-stats analytics

    We don't use Elasticsearch for flexible reports generation on the
    fuel-stats web UI, only for five fixed reports. Thus using of
    Elasticsearch is overhead and it can be removed from the servers
    Instead of Elasticsearch we use fuel-stats json api calls and
    PostgreSQL + Memcached.

    Changes list:

     - api call added to fuel-stats json api for data required on the web UI page,
     - column release added to DB installation_structures table schema,
     - memcached is used for caching data for the web UI page,
     - elasticsearch client removed from js requirement,
     - web UI page rewritten to use fuel-stats json api instead Elaticsearch.

    Co-Authored-By: Kate Pimenova <email address hidden>
    Change-Id: Ie752e0d0a3c80933888f986e2497b45adce730c9
    Closes-Bug: #1595548