Switch to sassc-rails as Ruby Sass is deprecated

Gemfile

@@ -4,6 +4,7 @@ gem 'appraisal', '>= 2.0'
 gem 'rails'
 gem 'haml'
 gem 'devise'
+gem 'sassc-rails'
 
 group :active_record do
   gem 'paper_trail'

gemfiles/cancan.gemfile

@@ -7,6 +7,7 @@ gem "rails", "~> 5.1.0"
 gem "haml"
 gem "devise", "~> 4.0"
 gem "sass-rails", "~> 5.0"
+gem "sassc-rails"
 
 group :active_record do
   gem "paper_trail"

gemfiles/rails_4.0.gemfile

@@ -7,6 +7,7 @@ gem "rails", "~> 4.0.0"
 gem "haml"
 gem "devise", ">= 3.2"
 gem "sass-rails", "~> 4.0.3"
+gem "sassc-rails"
 gem "test-unit"
 gem "capybara", ">= 0.8", group: :test
 gem "kaminari", "~> 0.14"

gemfiles/rails_4.1.gemfile

@@ -5,6 +5,7 @@ source "https://rubygems.org"
 gem "appraisal", ">= 2.0"
 gem "rails", "~> 4.1.0"
 gem "haml"
+gem "sassc-rails"
 gem "devise", ">= 3.2"
 gem "capybara", ">= 0.8", group: :test
 

gemfiles/rails_4.2.gemfile

@@ -7,6 +7,7 @@ gem "rails", "~> 4.2.0"
 gem "haml"
 gem "devise", ">= 3.4"
 gem "sass-rails", "~> 5.0"
+gem "sassc-rails"
 gem "capybara", ">= 0.8", group: :test
 
 group :active_record do

gemfiles/rails_5.1.gemfile

@@ -7,6 +7,7 @@ gem "rails", "~> 5.1.0"
 gem "haml"
 gem "devise", "~> 4.0"
 gem "sass-rails", "~> 5.0"
+gem "sassc-rails"
 
 group :active_record do
   gem "paper_trail", ">= 5.0"

gemfiles/rails_5.2.gemfile

@@ -7,6 +7,7 @@ gem "rails", "~> 5.2.0"
 gem "haml"
 gem "devise", "~> 4.4"
 gem "sass-rails", "~> 5.0"
+gem "sassc-rails"
 
 group :active_record do
   gem "paper_trail", ">= 5.0"

rails_admin.gemspec

@@ -17,6 +17,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'rails', ['>= 4.0', '< 6']
   spec.add_dependency 'remotipart', '~> 1.3'
   spec.add_dependency 'sass-rails', ['>= 4.0', '< 6']
+  spec.add_dependency 'sassc-rails', ['>= 1.3', '< 2']
   spec.add_development_dependency 'bundler', '~> 1.0'
   spec.authors = ['Erik Michaels-Ober', 'Bogdan Gaza', 'Petteri Kaapa', 'Benoit Benezech', 'Mitsuhiro Shibuya']
   spec.description = 'RailsAdmin is a Rails engine that provides an easy-to-use interface for managing your data.'