Build binary releases automatically

This branch improves the way releases are generated, so that we can release more easily (and thus more often?), and generate nightly binaries from BuildBot.

It is built on top of deployment/v2.1, needs some tweaks before merging for master (master renamed dist/ to scripts/dist/)

"Binaries" types:
* "PyPI packages", pure-Python source releases: source (sdist from distutils) and wheel (bdist_wheel from distutils) (see [PyPI page](https://pypi.python.org/pypi/vistrails))
* Anaconda package, binaries for the Conda package manager (see [binstar page](https://binstar.org/remram/vistrails))
* Mac binary with py2app
* Windows binary with Inno Setup