Dropping support for 2.7 in 2020

[Stuart Mumford]

Hi,
> It's very good to have Anaconda in such cases, as a last resort solution.
> The downside is that we lose the modularity of the scientific Python
> ecosystem, having to use a whole distribution in a very monolithic way. 

There is always miniconda which only installs Python and conda, which
means you can build up your own environments. Somewhat off topic, but we
have a nice centralised installation of miniconda on our cluster at
Sheffield.
(http://docs.iceberg.shef.ac.uk/en/latest/software/apps/python.html)

On topic, I am all for not releasing new (non-bug fix) versions of
libraries with Python 2.7 support in or even before 2020.

Stuart