Improve testing coverage after PR

# Problem

This [PR](https://github.com/code-corps/code-corps-ember/pull/1463#issuecomment-340201852) resulted in a substantial drop in test coverage (~1%) due to refactoring of imports. This seemingly shouldn't have an impact on testing coverage; however, the current thought is the imports from before this PR were picked up as covered by coveralls when in fact the actual logic was not covered. Here is an [example](https://coveralls.io/builds/13934987/source?filename=app%2Fmixins%2Fonboarding-controller.js).

Comienza con el ejemplo de Coveralls para app/mixins/onboarding-controller.js y compara su cobertura con los cambios de PR 1463, especialmente la refactorización de imports. Identifica la lógica que se informa como cubierta sin pruebas y, después, añade cobertura para ese comportamiento y verifica que el informe general ya no disminuya tras la refactorización.

Escrito por el modelo de indexación a partir del texto del issue.