without configuring the `MEDUSA_RENDERER_CLASS`, the staticsitegen command will fail
with an ImportError, rather than the NotImplementedError we expect.
Merge branch 'bugfix/unconfigured_render_class'
convert print usage to use the print function for py3 compatibility.
assume py2 by default, but if it fails, import the py3 stringIO and hope for the best.
doesn’t rely on six, or django’s vendored version of it.
open() needs to use ‘wb’ under py3 to avoid raising a TypeError about receiving bytes rather than str.
Merge branch 'feature/python3'