Script to get Pypy nightly builds

Started a script to download Pypy nightly builds and create virtualenvs for them. https://gist.github.com/stuaxo/5d4c0363317a875617271a6d424abbba

Virtualenvs are at ~/.virtualenvs where virtualenvwrapper can find them and named by pypy branch - e.g.

pypy-nightly-trunk
pypy-nightly-py3.5
Downloads only happen when there are new builds, and will resume if they were interrupted.