Travis builds should fail when scss-lint errors

[jglovier]

Expected behavior: When your styles fail the scss-linter, the build should fail in Travis.

Actual behavior: When your styles fail the scss-linter, the Travis build still passes.

Steps to reproduce: Branch, add some styles that don't pass the scss-linter, push your branch, and open a pull request to view the Travis build info.

You can paste the following style declaration into any stylesheet to produce scss-lint errors:

div#urmom > div.something.something span.wutwut + b.supdawg {
  width:100%;
  display:inline; 
  position:absolute; 
  color:rgba(0, 0, 0, 0.10)
}

I think if we can get the scss-lint to fail the ember build, that should produce the expected behavior in Travis, too. The whole point is to help enforce use of the linter and scaling our SCSS well.

cc @jkleinsc

[billybonks]

the pure node linter addon, that i linked previously generates a test suite for the Linting that should fail on travis

https://github.com/sir-dunxalot/broccoli-sass-lint/blob/master/index.js#L234

[jkleinsc]

If we are going to move to stylelint via #443, we should address this issue there.

[jglovier]

@billybonks yeah, we're planning to move to Stylelint asap to 🔥 Ruby as a dependency, and because it turns out Stylelint is even better (and faster) than scss-lint.

[billybonks]

https://www.npmjs.com/package/ember-cli-style-lint this solves this issue

[jglovier]

Closed in #488.