Consolidate declaration of DOC_TYPES to a single list

Author: tjgrathwell

app.rb

@@ -86,7 +86,7 @@ def ext
   def doc_path
     @doc_path ||= begin
       base = "#{site_dir}/#{params[:name]}"
-      %w{step md deck.md mw}.each do |ext|
+      Site::DOC_TYPES.each do |ext|
         path = "#{base}.#{ext}"
         return path if File.exist?(path)
       end

lib/site.rb

@@ -1,4 +1,6 @@
 class Site
+  DOC_TYPES = %w{step md deck.md mw}
+
   @@here = File.expand_path(File.dirname(__FILE__))
   @@project_root = File.dirname(@@here)
 
@@ -15,8 +17,6 @@ def self.named name, locale = "en"
     all(locale).detect{|site| site.name == name }
   end
 
-  DOC_TYPES = %w{step md deck.md mw}
-
   attr_reader :dir
 
   def initialize dir