Also matches recent updates to https://devcenter.heroku.com/articles/python-runtimes

Update pypy-1.9

Update pypy-1.8

1.7 --> 1.9 in two locations.

1.7 --> 1.8 in two locations.

Who was the 3.3.0 release manager? :)

/cc @GrahamDumpleton

This should fixe the mysterious collectstatic bug. (#143)

Use a default SLUG_ID value