Atma.js: update and refactor (closes GH-816)

TasteLang changes!

Columns are a bloody nightmare with a horribly broken implementation in Chrome.
This allows us to get rid of a bunch of fixed media queries (yay!) and instead
dynamically reflows into columns if the space allows.

CodeSchool AngularJS course link correction

Corrected the AngularJS CodeSchool course link

Correct verb tense.

The noun is plural ("practices"). The verb should match ("come").

Update Marionette to not be Maroon

fix link to app spec in index.html

Add prefixfree and adjust CSS

With prefixfree you don't need a devserver or anything to get the same look as
in the version built with gulp.

Changed `columns` to `column-count` to counter prefixfree bug here due to CSS
naming weirdness: https://github.com/LeaVerou/prefixfree/issues/54

fix links to app-spec.md

and "template/".

The rest of the gh-pages links look okay.

Gulp build chain

Fix #972

The script is going to build `master` with `gulp` on every push and, if
successful, push the resulting `dist/` to `gh-pages`.

Yay, autoprefixer!