Implemented Utils::execCmd for avoiding lua popen

Refreshed VS modules

scripts/lua/modules/vulnerability_scan/vs_utils.lua

@@ -912,12 +912,9 @@ function vs_utils.get_active_hosts(host, cidr)
       local s = string.split(host, '%.')
       local net = s[1].."."..s[2].."."..s[3].."."
       local command = 'nmap -sP -n ' .. net .. '1-254 | grep "Nmap scan report for" | cut -d " " -f 5'
-      local handle = io.popen(command)
-      local out = handle:read("*a")
+      local out = ntop.execCmd(command)
       local l = lines(out)
 
-      handle:close()
-
       for _,h in pairs(l) do
 	 result[#result+1] = h
       end