Update translations after pulling from Transfix + cleaning

As suggested in the release manager's checklist, this commit
introduces the results of re-pulling from transifex:

   tx pull -a -f

... and cleaning the .po files again:

   bundle exec rake gettext:clean
Update the .pot and .po files

These were updated with:

  bundle exec rake gettext:store_model_attributes
  bundle exec rake gettext:find