Running hiera task owerwrites plugin data files in the config

[Dmitry Ilyin]

Running hiera task will overwrite any modification to the hiera config file made by plugins

Plugin should has ability for re-define already existing data in hiera.
This need for just modify data for process it later by standart fuel manifests.

For example, plugin, than just disable OVS usage in network_scheme and configure network by standart netconfig task.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/240973

[Matthew Mosesohn (raytrac3r)]

The actual issue was corrected in running Hiera twice in master branch. Moving this to low and feature tag.

[Sergey Vasilenko (xenolog)]

Also plugin should has ability for re-define already existing in hiera data.
This need for just modify data for process it later by standart fuel manifests.

For example, plugin, than just disable OVS usage in network_scheme and configure network by standart netconfig task.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/240973
Committed: https://git.openstack.org/cgit/openstack/fuel-library/commit/?id=134d640af1d043e5649d384a2c33e1193473d65f
Submitter: Jenkins
Branch: master

commit 134d640af1d043e5649d384a2c33e1193473d65f
Author: Dmitry Ilyin <email address hidden>
Date: Mon Nov 2 22:27:08 2015 +0300

    Extend hiera task to improve plugin support

    * Add hiera_config type to mange hiera.yaml
    * Plugins can put their overrides to /etc/hiera/plugins/
    * Running hiera_config again will gather override files
      and insert records for them to the main config file after
      the basic elements
    * Or, it metadata_yaml_file is present, hiera_config can
      take the list of enabled plugins and add records for them
      instead of scanning the plugins directory

    Closes-Bug: 1512456
    DocImpact: add information about placing plugin data files to /etc/hiera/plugins/ instead of other files.
    Change-Id: Ifdb27708a2457e8c1430695bb2412594806d211f