Make backwards compatible with Python 2

[msonderegger]

Outstanding from #82 : we want python scripts to still run if user using Python 2, for backwards compatibility since AutoVOT is incorporated into various researchers' pipelines.

seems like it'll just work to do an update like
https://python-future.org/quickstart.html
"To convert existing Python 3 code"

also will mean changing crunch-bang statement

suggested by @jkeshet