* Use I18n.locale instead of ":en"
* Reset I18n.locale value after locale changing tests

* Improve default language decision

This change allows to takes account of accepted language determined by
the user agent even if the custom default locale of the instance is
configured.

* Cover Localized more

* Fix code style

* Coverage for rate limit headers

* Move rate limit headers methods to concern

* Move throttle check to condition on before_action

* Move match_data variable into method

* Move utc timestamp to separate method

* Move header setting into smaller methods

* specs cleanup

* Remove methods from ObfuscateFilename

* Spec ObfuscateFilename