Change before_filter to before_action

[Qqwy]

When following the instructions in the readme, Rails 5.0 will show a deprecation warning that before_filter is deprecated, and that before_action should be used instead.

So I think that

# app/controllers/application_controller.rb
class ApplicationController < ...
  before_filter :set_gettext_locale

should be changed to

# app/controllers/application_controller.rb
class ApplicationController < ...
  before_action :set_gettext_locale

[grosser]

yes! please make a PR!

[neohunter]

Created PR