Merge branch 'refactor-pickedversions' of https://github.com/jaap3/buildout into jaap3-refactor-pickedversions

Removed data_files from setup.py, which was installing README.rst in current directory during installation

Bump version to indicate change in dependencies.

We don't need to juke faking setuptools (or not) when we are using
setuptools rather than distribute.

Even if distutils / setuptools gives it to us more than once.

Use that normalizer everywhere.

My doctest / renormalizer fu is not strong enough to deal with the
changes to output:

- setuptools now has dependencies, and emits output to add them as
  'find-links'.  I tried adding an 'adding_find_link' renormalizer,
  but it doesn't suppress the output.

- Other failures due to merge tweaking APIs, etc.  Again, I'm not
  competent to fix them in the doctest / renormalizer world:  they make
  my head hurt.

This includes renaming `store_picked_versions` to `store_required_by`
to better signify its intent and adding `get_picked_versions`
to `zc.buidlout.easy_install`.

change entries.

Fixed several tiny typos.

This is weird, platform.python_version_tuple() returns a tuple of ints
on Python 2.6 on windows.

added conditional section documentation

Removed data_files from setup.py, which was installing README.rst in current directory during installation

Fixed the conditional-section example and added a test for it.

Added some more details about option overridding.

       exist in that branch).  I don't really expect people to use
       conditional sections with parse, but behavior should be
       consistent.