Added license information

This is free to use for any purpose you see fit.

post-like.php

@@ -5,6 +5,22 @@
 Version:      0.3.3
 Author:       Jon Masterson
 Author URI:   http://jonmasterson.com/
+
+License:
+Copyright (C) 2014 Jon Masterson
+
+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 3 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, see <http://www.gnu.org/licenses/>.
 */
 
 /**