We should vendor the Pyston macrobenchmarks #474

The Pyston macrobenchmarks currently live at https://github.com/pyston/python-macrobenchmarks. They're really good benchmarks that are already pyperformance-compatible (and we make a habit of running them anyways), but running them requires cloning a separate repo locally, passing a MANIFEST path to pyperformance, etc. Special-casing is also required on doesjitgobrrr.com to make links to benchmark sources work for both repos.

We should officially pull copies of these benchmarks into the repo. CC @savannahostrowski.