Merge branch 'rs-revert-remove-filters' into 'master'

Revert "Remove the `:coffee` and `:coffeescript` Haml filters"

This reverts commit ae7de2f8.

Several files in EE still use the `:coffeescript` filter and
I don't have time to fix them before the CE-to-EE merge.

See https://gitlab.com/gitlab-org/gitlab-ee/builds/553647

I will reintroduce this change in a future MR.

See merge request !2400

config/initializers/haml.rb

 Haml::Template.options[:ugly] = true
-
-# Remove the `:coffee` and `:coffeescript` filters
-#
-# See https://git.io/vztMu and http://stackoverflow.com/a/17571242/223897
-Haml::Filters.remove_filter('coffee')
-Haml::Filters.remove_filter('coffeescript')