Remove redundant exclamation marks by using Psych 2.0.0 on all locales

This changes are done by [Psych](https://rubygems.org/gems/psych) (version 2.0.0).

I also sorted keys in all locales using [i18n_yaml_sorter](https://github.com/redealumni/i18n_yaml_sorter).
I think we shouldn't remove comments.