Revert "Drop python2 support"

This reverts commit fb1dc7c405f6114687338382149bfc775597935a.

I was under the impression, that all previous scripts were already
working with python 3. But as it turns out, this isn't true. Reverting,
so I can properly post follow-up patches, that fix the issues before we
apply this "drop python2" patch again.

Related: OS#2819
Change-Id: Ic1559d1a9f7839fa86a841d62a04b22e1caed466
13 files changed