Parts should be installable via pip install

[Marc Valle]

As someone who wants to build a parts based project, I want to be able to install parts via pip so that I can avoid setup problems.

Acceptance criteria:

1. pip install parts (or whatever the name of the package will be... scons-parts?) installs parts and all its dependencies (scons)

We have been running into issues where folks not very familiar with python installation are installing some things via windows installer some things via zips etc... Registering parts on PyPy should make parts installation easier.

[Jason Kenny]

Fix with 0.12 drop of Parts