use python2 interpreter

this brings back an old issue, a change to using (correct) python2 interpreter, this avoids problems with execution of the scripts on systems where default python is python3. This will remove need for running in virtualenv on many systems and simplify packaging for distros. 

Warning: this was merged using ours strategy to master (git merge -s ours py2), maybe will need this done manually for upstream. (ie. doesnt show 'files changed', need to look at commits manually, also, you can see commits modifying old (non-existing) files, merging with -s ours it's ok, these don't get created.)