[freeipa PR#1024][opened] py3: turn all shebangs to python3

[stlaz]

   URL: https://github.com/freeipa/freeipa/pull/1024
Author: stlaz
 Title: #1024: py3: turn all shebangs to python3
Action: opened

PR body:
"""
This patchset turns all shebangs in IPA scripts to Python 3. Note that this may seem like
going against what we agreed on some two months ago but the outcome to turn everything to
`/usr/bin/python` to use default python version would be a setback in the Fedora planning:
https://fedoraproject.org/wiki/FinalizingFedoraSwitchtoPython3 and there is no reason not
to use the up-till-now long running Python 3 effort.

This also required to regenerate the `API.txt` file so that our checks don't fail to
validate for python2/3 type discrepancies.
"""

To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/1024/head:pr1024
git checkout pr1024