Allow SMBDirect to be optional

The smb_version module needs to deregister the SMBDirect option,
but cannot do this because SMBDirect is a required option. By
having it as optional, the user no longer needs to set it. Also,
since SMBDirect already has a default value, having it as optional
should not change the mixin's default behavior.

Author: wchen-r7

lib/msf/core/exploit/smb/client.rb

@@ -45,7 +45,7 @@ def initialize(info = {})
 
         register_advanced_options(
         [
-          OptBool.new('SMBDirect', [ true, 'The target port is a raw SMB service (not NetBIOS)', true ]),
+          OptBool.new('SMBDirect', [ false, 'The target port is a raw SMB service (not NetBIOS)', true ]),
           OptString.new('SMBUser', [ false, 'The username to authenticate as', '']),
           OptString.new('SMBPass', [ false, 'The password for the specified username', '']),
           OptString.new('SMBDomain',  [ false, 'The Windows domain to use for authentication', '.']),