Update expected python version brew
Add warning about homebrew and ports
Add IPython dependencies

 because https://github.com/pypa/pip/pull/1896 is still not in a released version of pip
Merge pull request #14 from jenshnielsen/staging

Staging
Merge pull request #15 from MattClarkson/staging

Splitting slides for layout.
update notebook copy and analysis.py -> analyzer.py
Session 2
Link to session 2 in leftnav
Link in session 2 content