Upgrade sass-rails

What does this MR do?

Upgrades sass-rails from 5.0.4 to 5.0.5. Includes support for Rails 5.

Changelog: https://github.com/rails/sass-rails/releases

Working toward #14286 (moved)

Does this MR meet the acceptance criteria?

• Tests
  • All builds are passing
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together