Make mongodb-info and mongodb-databases default as they're fast, safe,

and give good information.

scripts/mongodb-databases.nse

@@ -34,7 +34,7 @@ Attempts to get tables from a MongoDB
 
 author = "Martin Holst Swende"
 license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
-categories = {"discovery", "safe"}
+categories = {"default", "discovery", "safe"}
 
 require "mongodb"
 require "shortport"
@@ -71,4 +71,4 @@ function action(host,port)
 	if result ~= nil then
 		return stdnse.format_output(true, output )
 	end
-end
+end