Revert "Remove future lessons"

This reverts commit 273caa6f0a91646e2a212bdec804734b9d709dc5.
Start to work on lessons 5 and 6
Merge branch 'master' into staging

* master:
  Show code as well as results for bash fragments
Coding conventions section
Comments section for session 5
Tweaks to comments section
Add notes on using Sphinx
Tweak deploy script to match new filter
Notes on refactoring
Object-oriented refactorings
Fix bugs in pycon fragments, and add assertion to dexy build to prevent recurrence
Hide future lessons again on master branch