Clean up local variable usage - Zaqar

Change-Id: Ie274ce587134d3a3a928a3825dc4452298c5c4d0
Configure enabled and disabled extensions in tempest

This patch adds support for configuring the api_extensions
option of the various feature-$service-(enabled|disabled)
sections in tempest's configuration file.

Please note that enabled extensions for the object storage
service are specified in tempest using the discoverable_apis
configuration options.

Partially-implements: Blueprint branchless-tempest-extensions

Change-Id: Ib64c0a474b153f42f3a4a427d86275c85f107997
Add docs environment to tox.ini

As per the governance resolution https://review.openstack.org/119875,
projects should have a docs environment in their tox.ini testing
interface. Add one.

Change-Id: Ib3548bc23713e120089ae29b5c4e851de48cf8d3
Merge "Add docs environment to tox.ini"
Merge "Clean up local variable usage - Zaqar"
Merge "Configure enabled and disabled extensions in tempest"
Merge branch 'master' of https://github.com/openstack-dev/devstack