As of now, the glossary defined in our documentation reflects the
current state of the codebase. In order to avoid any discrepancy
between the codebase and each definition, the objective here is to
gather both in a single place and link it into the rst documentation
via a custom directive.
Also re-aligned the requirements with liberty for doc.
DocImpact
Change-Id: I9ca50f8d3c32b4690ee240e13dec0cb7eeedcc2c
Update requirements.txt and test-requirements.txt from Global Requirements
defined into openstack/requirements project (stable/liberty).
Change-Id: I9ecbf5a7fb2c38624cc4f52b13515f8af75a4889
Closes-Bug: #1513118
