Land rapid7#2968, missing powershell require

Author: egypt

modules/exploits/windows/local/powershell_cmd_upgrade.rb

@@ -4,6 +4,7 @@
 ##
 
 require 'msf/core'
+require 'msf/core/exploit/powershell'
 
 class Metasploit3 < Msf::Exploit::Local
   Rank = ExcellentRanking