Standardize the @copyright fields of NSE modules; change "See nmaps COPYING for

license" to "Same as Nmap--See http://nmap.org/book/man-legal.html" like
scripts commonly use. I added the field to some modules I know to be under the
Nmap license: bin, datafiles, dns, nmap, unpwdb. I left alone bin, bit, pcre,
and url, which come from outside sources.

nselib/dns.lua

@@ -2,6 +2,7 @@ module(... or "dns", package.seeall)
 
 --- Simple DNS library supporting packet creation, encoding, decoding,
 -- and querying.
+-- @copyright Same as Nmap--See http://nmap.org/book/man-legal.html
 
 require("ipOps")
 require("stdnse")