Fix two minor style things.

There is a pep8 indentation issue and an unused import. Fix them here
so I can verify that my later patches don't regress and become unhappy.
Add hook point to process setup_requires.
Install setup_requires items.

If pip isn't around, use easy_install to do the only thing that it's
good for, which is installing pip.

Once we have pip, use that to install all of the setup_requires needs
in one go.
Filter attributes through filter plugins.

If anything on the system has defined d2to1 filter plugins, use them
to process the attrs before we re-initialize.