This makes Heroku/Vagrant use Python 3.6.8 instead of Python 2.7, and
inverts the versions used in the Travis testing matrix - leaving all
unit tests running against Python 2.7 to make it easier to roll back
if needs be. The Vagrant provision script and Heroku Python buildpack will
automatically detect the changed Python version and purge the existing
installation/site-packages prior to installing the new version.
We're using Python 3.6 rather than 3.7, since latest Celery/Kombu do not
yet support Python 3.7 (and we're on an older version anyway; bug 1337717).
Bug 1529243 is filed for updating to Python 3.7 later.
Prevents:
```
kombu/five.py:20: DeprecationWarning: the imp module is deprecated in favour of importlib ...
markdown/util.py:453: DeprecationWarning: Using the add method to register a processor or pattern is deprecated ...
newrelic/api/import_hook.py:166: DeprecationWarning: Use importlib.util.find_spec() instead
```
To help surface deprecation warnings more visible when running
Django commands locally (rather than just when running pytest).
These will not cause the command to fail.
Since they're not specific to the Django app 'webapp'.
Whilst we're there, the local & example settings files have been
renamed. In the future I'd like to combine settings_local.example.py
with puppet/files/treeherder/local.vagrant.py, but I'll do that in
another bug.
The MPL 2.0 terms state that as long as a LICENSE file is present, the
per-file header text is not required. See "Exhibit A" at the end of:
https://www.mozilla.org/MPL/2.0/
Armen Zambrano
Ed Morley
Ed Morley
Jonathan French
Cameron Dawson
mdoglio