[WIP] setup.py revamp

As pointed out in NeuroStars:

http://neurostars.org/p/73/

I've started refactoring the installation process with nipype as part of the Leiden hackathon 2014:

http://wiki.incf.org/mediawiki/index.php/Hackathons/Leiden-2014

There are some remaining issues with docs building (via cmdclass) and versioning. I'm thinking on migrating to a simple `Makefile` like we do in logbook:

https://github.com/brainstorm/logbook/blob/master/Makefile#L24

Feedback/testing/comments are welcome!