Add short section on setuptools

This improves the situation because it eliminates the constraints on packages
outside of pip, and leads to a reduction in <pkg>-whl packages in the archive.

files.  No actual change in policy is made.

    - Reflect disuse of pyshared directory in favor of /usr/lib/python2.7/
      dist-packages since python2.7 is the last and only python version
      supported (Closes: #763451)
    - Update python-central information to reflect its removal from Jessie

* Add myself to Uploaders.
* Add python policy for Python Wheels.

    - Describe addition of /usr/bin/python2 due to upstream changes
    - Remove redundant text on Python provides and clarify when they should be used
    - Update description of functionality related to X-Python-Version for Wheezy
    - Update X/XS-Python-Versions to also include X-Python-Version examples

  * Drop python2 symlink pending further discussion
  * Update recent Python policy changes based on feedback from Debian Python

    - Add deprecation information about python-central and python-support
    - Clarify Python module and package descriptions

  * Start Python Policy updates for Wheezy
    - Document current practice to not provide /usr/bin/python2
    - Strengthen warning aginst using /usr/bin/env python     
    - Update paths section for python2.7 and python3
    - Deprecate XB-Python-Version
    - Clarify use of {python:Provides}
    - Clarify that build-dependencies on -dev packages should not be used
      except when required

    Adam D. Barratt)