* replace ember-cp-validations with custom validation logic for poll creation
* refactor poll participation to not use ember-cp-validations
* drop ember-cp-validations from create.settings route
* remove unused leftovers from ember-cp-validations
* fix potential leak
* assertion thrown in CI tests (Firefox) indicate that listener is cleaned up automatically
* synchronize translations
* mark string as html safe before passing to translation instead of bypassing HTML escape using {{{unsafe}}} syntax
* replace ember-i18n with ember-intl