Bindep files expect python2-pyOpenSSL to be present

[Major Hayden]

The bindep.txt files in OSA repositories expect python2-pyOpenSSL to be installed, but this package is only available from the RDO QEMU repository. This works in the gate jobs now because the CentOS image has lots of repositories enabled by default.

We should:

1) Limit the number of repositories enabled in a standard CentOS gate job
2) Adjust bindep.txt to use pyOpenSSL rather than python2-OpenSSL

This will make the gate jobs look more like a normally-installed CentOS system and it will allow dnf to work properly (since dnf fails when it can't install python2-OpenSSL).

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/490513
Committed: https://git.openstack.org/cgit/openstack/openstack-ansible-tests/commit/?id=4e3d92e7152b39884cb09e24459c2f33bd965078
Submitter: Jenkins
Branch: master

commit 4e3d92e7152b39884cb09e24459c2f33bd965078
Author: Major Hayden <email address hidden>
Date: Thu Aug 3 10:35:28 2017 -0500

    Install pyOpenSSL on CentOS

    python2-pyOpenSSL is only available from the CentOS RDO QEMU repo
    and that repo is not commonly installed on a basic CentOS 7 system.
    It happens to be pre-installed in the OpenStack CI gates and that's
    why this bindep file works.

    However, this package installation fails on a normal CentOS 7
    system and it can cause problems during deployment or testing.

    The EPEL repository has a package called pyOpenSSL that provides
    python bindings for OpenSSL on CentOS systems. That should be used
    instead.

    In addition, dnf will fail entirely with a bad exit code if a package
    isn't found. The yum package manager will trudge on without errors.

    Closes-Bug: 1708493
    Depends-On: I2ac5a9c463991e4668a3e7608831c1944377e85e
    Change-Id: I93de939304b57a211f2eb281365d5a591752be7d