Added LICENSE file

LICENSE

@@ -0,0 +1,15 @@
+Copyright (C) 2014 Jack-Benny Persson <jack-benny@cyberinfo.se>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

README.md

@@ -5,6 +5,10 @@ will get with a 26 bit netmask, simply run the script as below:
 
     php netcalc.php 26
 
+Or you `chmod +x netcalc.php` and run it as below:
+
+    ./netcalc.php 26
+
 The above command will give you the following outut:
 
     Netmask

netcalc.php

@@ -1,3 +1,4 @@
+#!/usr/bin/php
 <?php
 
 /*