Bump to version 2.5.2

Gemfile.lock

 PATH
 PATH
   remote: .
   remote: .
   specs:
   specs:
-    paperclip (2.5.1)
+    paperclip (2.5.2)
       activerecord (>= 2.3.0)
       activerecord (>= 2.3.0)
       activesupport (>= 2.3.2)
       activesupport (>= 2.3.2)
       cocaine (>= 0.0.2)
       cocaine (>= 0.0.2)

lib/paperclip/version.rb

 module Paperclip
 module Paperclip
-  VERSION = "2.5.1" unless defined? Paperclip::VERSION
+  VERSION = "2.5.2" unless defined? Paperclip::VERSION
 end
 end