Fixing capitalization
Making rebuild depend on ./index.html
1. Adding syllabus with point-form summary of topics to generic home page.
2. Adding links to reference guides.
3. Putting generic calendar in two-column format.
Replacing 'coffee will be served' with 'coffee break'
Added newline in numpy lesson to fix formatting
Merge pull request #500 from zonca/numpy_lesson_fix

Bugfix: added newline in numpy lesson to fix formatting
Fix rendering of code block

Also add $ to tell input from output
1. Adding `helper` field to header (like `instructor` field).
2. Updating `README.md` to explain what it's for.
3. Updating index page validator to check `helper` field.
Merge pull request #494 from gvwilson/adding-topics-to-standard-homepage

Adding syllabus to default home page.
Addressing comments by @r-gaia-cs
Adding back the glossary checker
Making placeholders for missing glossary entries
Removing parable about startups and education: snarky, and not really informative
Tidying up bib entries
Reformatting bibliography
Converting to individual challenge div's in the novice shell lessons
Converting to single-div-per-challenge in novice Git tutorial
Explaining that argument vs. parameter is inconsistent
Cleaning up glossary definitions of argument and parameter
Merge pull request #506 from gvwilson/adding-helpers-to-home-page

Adding helper field to home page template.