[doc] Use taskflow library for building and executing action plans

[OpenStack Infra]

https://review.openstack.org/264142
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/watcher" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit 0e7bfe61bdbaa059b80e705e1411f7702be91a3d
Author: Jean-Emile DARTOIS <email address hidden>
Date: Wed Jan 6 12:44:25 2016 +0100

    Use taskflow library for building and executing action plans

    The aim of this patchset is to integrate taskflow in
    the Watcher Applier. Taskflow will help us a lot to make
    Action Plan execution easy, consistent, scalable and reliable.

    DocImpact

    Partially implements: blueprint use-taskflow

    Change-Id: I903d6509d74a61ad64e1506b8a7156e6e91abcfb
    Closes-Bug: #1535326
    Closes-Bug: #1531912

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/279084
Committed: https://git.openstack.org/cgit/openstack/watcher/commit/?id=98a65efb163f8c00f4af06a45f7dfa51633b31cc
Submitter: Jenkins
Branch: master

commit 98a65efb163f8c00f4af06a45f7dfa51633b31cc
Author: Vincent Françoise <email address hidden>
Date: Thu Feb 11 14:49:19 2016 +0100

    RST directive to discover and generate drivers doc

    This patchset introduces a new custom directive called 'drivers-doc'
    which loads all available drivers under a given namespace and import
    their respective docstring into the .rst document.

    This patchset also contains some modification/addition to the
    docstring of these drivers to make the final document complete.

    Change-Id: Ib3df59fa45cea9d11d20fb73a5f0f1d564135bca
    Closes-Bug: #1536218
    Closes-Bug: #1536735