Support other SASS engines

Author: Matija Čupić

lib/bootstrap/engine.rb

@@ -7,7 +7,15 @@
   begin
     require 'sassc-rails'
   rescue LoadError
-    raise LoadError.new("bootstrap-rubygem requires a Sass engine. Please add dartsass-sprockets or sassc-rails to your dependencies.")
+    begin
+      require 'dartsass-rails'
+    rescue LoadError
+      begin
+        require 'cssbundling-rails'
+      rescue LoadError
+        raise LoadError.new("bootstrap-rubygem requires a Sass engine. Please add dartsass-sprockets, sassc-rails, dartsass-rails or cssbundling-rails to your dependencies.")
+      end
+    end
   end
 end