Big commit to turn project pages into grids of screenshots

Project pages (HTML, JavaScript, Stencyl) now load the student games as hyperlinked images in a 3-col grid.

1) took screenshots for all games.  they are stored in the game's folder (e.g. games/HTML/Student 01/)
2) Switch from using python to using liquid to generate the HTML for the kraken 3-col grid
3) small css tweaks to get the kraken grid to play nicely
4) tweaked the game post page generator to fit with the above changes