Fix internationalization for checkbox label on sign in page.
Localize navigation content.
Rename and move "users" navigation item to the left side.
Enable "users" menu item for "superadmin" role, too.
Localize sign_in spec.
Add localized title strings to links in devise views.
Localize sign out spec.
Merge branch 'feature/devise-i18n-views' into prototype

+ Please mind that the localization is not finished for all devise views yet.