Fix Zip Export and Print View

Fix http://bug.to/issues/show/335
and
http://bug.to/issues/show/334

We now bundle the uploaded files directory
(and the public/ directory for the (X)HTML
export) in the Zipball when exporting a Web.

Also, correct the Print View to produce proper links
uploaded files.

app/helpers/application_helper.rb

@@ -127,9 +127,4 @@ require 'stringsupport'
     end
   end
 
-  def darken(s)
-     n=s.length/3
-     s.scan( %r(\w{#{n},#{n}}) ).collect {|a| (a.hex * 2/3).to_s(16).rjust(n,'0')}.join
-  end
-
 end