[stats] Add OSWL statistics collector user to the env

[Aleksey Kasatkin]

Additional user with read-only rights is required for collection of OSWL statistics.
It can be called e.g. workloads_collector. Ability to set password for the user should be provided in UI.
Cluster attributes should have section with user parameters to be passed to orchestrator.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/160418

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/160418
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=dcaada087595013462636da77859a9a9ca4e9d19
Submitter: Jenkins
Branch: master

commit dcaada087595013462636da77859a9a9ca4e9d19
Author: Aleksey Kasatkin <email address hidden>
Date: Mon Mar 2 18:54:50 2015 +0200

    Add parameters for OSWL collector user

    Implements: blueprint openstack-workload-statistics
    Related-Bug: #1427270

    Change-Id: I86c0b1b5027b26d07b2d3502c778a151af45b54f

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/160759
Committed: https://git.openstack.org/cgit/stackforge/fuel-library/commit/?id=bdf6197f81ba129f7bdf7c78c33da17ba06eb774
Submitter: Jenkins
Branch: master

commit bdf6197f81ba129f7bdf7c78c33da17ba06eb774
Author: Matthew Mosesohn <email address hidden>
Date: Tue Mar 3 16:03:59 2015 +0400

    Add OSWL collector keystone user

    Adds keystone user for gathering OpenStack
    workload statistics. A separate user is needed
    in case the administrator changes the default
    user credentials. Further details about OSWL
    collector in blueprint.

    Change-Id: Idfc669b882c2c32a3805b36ffc58b27c58048e6d
    blueprint openstack-workload-statistics
    Closes-Bug: #1427270