Emit console warnings in addition to test failures.

[rwjblue]

Basically similar to ember-cli-eslint, you get both a warning in the console and a failing test.

Links:

• https://github.com/ember-cli/ember-cli-eslint/blob/master/index.js#L67-L75 - passing in a custom console that uses this.ui.writeLine
• https://github.com/ember-cli/broccoli-lint-eslint/blob/master/lib/index.js#L205 - Emit results to this.console.log