Ensure i18n keys are filled correctly, refs #7322

Squashed commit of the following:

commit 38a97e484410796d279f3d99797958b8df9ea29d
Author: Mike Gale <mikeg@artefactual.com>
Date:   Tue Sep 30 15:34:27 2014 -0700

    Ensure i18n keys are filled correctly ref #7322

commit fe1f95bcddf2cfc3eb0a5d5b695908341e8354cf
Author: Jesús García Crespo <jesus@sevein.com>
Date:   Tue Sep 30 13:25:42 2014 -0700

    Add test for #7322

    Run: php symfony test:unit issue7322