Change ExcellentRanking to GoodRanking for MS14-064

The ms14_064_ole_code_execution exploit's ranking is being lowered
to GoodRanking because of these two reasons:

1. The vulnerable component isn't in Internet Explorer. And BES can't
   check it so the exploit still fires even if the target is patched.
2. Although rare, we've seen the exploit crashing IE, and since this
   is a memory curruption type of bug, it should not be in Excellent
   ranking anyway.

Author: wchen-r7

modules/exploits/windows/browser/ms14_064_ole_code_execution.rb

@@ -8,7 +8,7 @@
 require 'msf/core/exploit/powershell'
 
 class Metasploit4 < Msf::Exploit::Remote
-  Rank = ExcellentRanking
+  Rank = GoodRanking
 
   include Msf::Exploit::Remote::BrowserExploitServer
   include Msf::Exploit::EXE