Merge pull request #1 from qcubed/rc-2.2.1

Rc 2.2.1
Estonian language file added

I dare to believe that the Estonian language file (et.po) could be
represented there includes/qcubed/_core/i18n in folder.
Merge branch 'master' of https://github.com/kukrik/framework into feature-321
Merge pull request #324 from qcubed/feature-321

Estonian language file adding