Move open3 require into msfvenom helper

Author: rastating

payloads/meterpreter_bind_tcp.rb

@@ -1,5 +1,3 @@
-require 'open3'
-
 module Wpxf::Payloads
   # A Meterpreter bind TCP payload generator.
   class MeterpreterBindTcp < Wpxf::Payload

payloads/meterpreter_reverse_tcp.rb

@@ -1,5 +1,3 @@
-require 'open3'
-
 module Wpxf::Payloads
   # A Meterpreter reverse TCP payload generator.
   class MeterpreterReverseTcp < Wpxf::Payload

payloads/msfvenom_helper.rb

@@ -1,3 +1,5 @@
+require 'open3'
+
 # Provides common functionality for generating payloads using msfvenom.
 module Wpxf::Payloads::MsfVenomHelper
   include Wpxf