Sort the docs based on path

lib/jekyll/collection.rb

@@ -19,7 +19,7 @@ module Jekyll
           docs << doc
         end
       end
-      docs
+      docs.sort!
     end
 
     def directory

lib/jekyll/document.rb

@@ -1,5 +1,6 @@
 module Jekyll
   class Document
+    include Comparable
 
     attr_reader   :path, :site
     attr_accessor :content, :collection
@@ -88,5 +89,9 @@ module Jekyll
       })
     end
 
+    def <=>(anotherDocument)
+      path <=> anotherDocument.path
+    end
+
   end
 end