Merge branch 'release-1.6.8' into develop

* release-1.6.8:
  Bumping version to 1.6.8
Add pipes to list of py2exe packages

This is imported via six dynamically so we don't pick
up on the module as a required import.
Merge branch 'fix-py2exe' into develop

* fix-py2exe:
  Add pipes to list of py2exe packages
Updated six to use six vendored in botocore
Switch many of the files to new six format
Merge pull request #1057 from kyleknap/vendor-six

Use botocore vendoring of six
Rename --version to --pipeline-version

Fixes an issue where ``aws datapipeline get-pipeline-definition``
exposed a ``--version`` argument which was shadowed by the top level
``--version`` argument.  This is similar to what was done for
the ``--query/--objects-query`` argument.
Merge branch 'datapipeline-rename' into develop

* datapipeline-rename:
  Rename --version to --pipeline-version
Update changelog with latest features
Update feedback link to the newest/correct value
Add elastictranscoder to the latest version
Bumping version to 1.6.9
Merge branch 'release-1.6.9'

* release-1.6.9:
  Bumping version to 1.6.9
  Add elastictranscoder to the latest version
  Update feedback link to the newest/correct value
  Update changelog with latest features
  Rename --version to --pipeline-version
  Switch many of the files to new six format
  Updated six to use six vendored in botocore
  Add pipes to list of py2exe packages