Add a missing post require

Author: todb

modules/post/windows/gather/enum_proxy.rb

@@ -10,6 +10,7 @@
 ##
 
 require 'msf/core'
+require 'msf/core/post/windows/services'
 
 class Metasploit3 < Msf::Post
 
@@ -108,4 +109,4 @@ def run
 
 	end
 
-end
+end