Simplify development box provisioning with Vagrant

This pull request replaced all existing provisioning steps with a shell script-based one tailored for development. Production deployment from now on will be done with Docker (see also [pxfs/fanboi2-docker](https://github.com/pxfs/fanboi2)). This pull request also changed from [CPython 3.2](https://www.python.org/download/releases/3.2.5/) to [PyPy3 2.3](http://pypy.org/download.html).