In order to create a virtualenv with tox, a postgresql package is needed
as a prerequisite. The dev-quickstart documentation has been updated to
reflect this.
In addition, the prerequisites for Fedora/RHEL were modified, because
mysql-devel is needed, not mysql-libs.
Fixes bug: #1227390
Change-Id: Ibfdb0a9a3d560fcc3fb7d95aaa1d765ed18215e2