F23 System Wide Change: Python 3 as Default

[Colin Walters]

On Wed, Jun 10, 2015, at 08:50 AM, Jan Kurik wrote:
> 
>     * Python 3 is the only Python implementation in Atomic host

That's not going to happen unless Ansible learns how to deal
with Python 3 at least:

https://lists.fedoraproject.org/pipermail/devel/2015-January/206903.html

So again, this change is very likely to be "Add Python 3 by default and port a lot of things" at least for the base Server and Atomic Host".  Other configurations like the Docker base image are more realistic to have Python 3 only.