Ensure specified python interpreter and development files are installed

.. note:: This role is only available for Debian based platforms
          currently.

**Role Variables**

.. zuul:rolevar:: python_version

  Optional version of python interpreter to install, such as ``3.7``.

.. zuul:rolevar:: python_use_pyenv
   :default: False

   Whether to optionally use pyenv to install python instead of distro
   packages.