simplify haml renderer

lib/middleman/renderers/haml.rb

@@ -1,11 +1,12 @@
-require "haml"
+module Middleman::Renderers::Haml
-require "coffee-filter"
-
-module Middleman
-  module Renderers
-    module Haml
   class << self
     def registered(app)
+      # Base library
+      require "haml"
+
+      # Coffee-script filter for Haml
+      require "coffee-filter"
+      
       app.helpers Helpers
     end
     alias :included :registered
@@ -17,5 +18,3 @@ module Middleman
     end
   end
 end
-  end
-end