Deployment graph tasks parameters now saved in Transaction before deployment

[OpenStack Infra]

https://review.openstack.org/321096
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.

commit 11015024801fb7bcadd1919ada2196f593a765df
Author: Ilya Kutukov <email address hidden>
Date: Thu Apr 7 21:59:16 2016 +0300

    Deployment graph tasks parameters now saved in Transaction before deployment

    Deployment tasks snapshot is now saving during DeploymentTask message creation
    in Transaction.tasks_snapshot field.

    Methods:

        * attach_tasks_snapshot
        * get_tasks_snapshot

    are added to Transaction model.

    Handler /transactions/:transaction_id/deployment_history/
    now showing tasks parameters in output and supporting
    request parameter:
    /transactions/:transaction_id/deployment_history/?tasks_names=task1,task2

    Change-Id: I59446ef456f7d3bd249c686b7a8e1a93a364daf2
    Partial-Bug: #1563317
    DocImpact

[Olga Gusarenko (ogusarenko)]

This is API-related, marking as invalid as Fuel docs do not contain API reference for now.