fixed issue with the docs not building due to an issue with ssl library

There was an issue with building the docs, most likely related to this issue: https://github.com/boto/botocore/issues/266 I made a few changes to the Dockerfile, and I got it to work locally.

This was tested by @fredlf who was the original reporter.

@vieux can you test to see if it fixes your issues as well? 
Really unrelated, but while at it, should dockers' own Dockerfiles follow the "best practice" guidelines? In this case; multiline and alphabetically; https://docs.docker.com/articles/dockerfile_best-practices/#sort-multi-line-arguments