Lua 5.2 upgrade [1] for NSE.

[1] http://seclists.org/nmap-dev/2012/q2/34

scripts/http-litespeed-sourcecode-download.nse

@@ -1,3 +1,9 @@
+local http = require "http"
+local nmap = require "nmap"
+local shortport = require "shortport"
+local stdnse = require "stdnse"
+local string = require "string"
+
 description = [[
 Exploits a null-byte poisoning vulnerability in Litespeed Web Servers 4.0.x before 4.0.15 to retrieve the target script's source code by sending a HTTP request with a null byte followed by a .txt file extension (CVE-2010-2333).
 
@@ -31,8 +37,6 @@ author = "Paulino Calderon"
 license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
 categories = {"vuln", "intrusive", "exploit"}
 
-require "http"
-require "shortport"
 
 portrule = shortport.http