Bulk (mostly documentation) update

 - Remove PHP version from license notices
 - Bump year number in copyright notices
 - Recommend PHP 5.4 or newer to be used
 - Tell Travis-CI to test on PHP 5.3.0 instead of the latest 5.3 version

Related: #3450
diff --git a/index.php b/index.php
index 92c92c0..ba0ba67 100755
--- a/index.php
+++ b/index.php
@@ -2,11 +2,11 @@
 /**
  * CodeIgniter
  *
- * An open source application development framework for PHP 5.2.4 or newer
+ * An open source application development framework for PHP
  *
  * This content is released under the MIT License (MIT)
  *
- * Copyright (c) 2014, British Columbia Institute of Technology
+ * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -29,7 +29,7 @@
  * @package	CodeIgniter
  * @author	EllisLab Dev Team
  * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
- * @copyright	Copyright (c) 2014, British Columbia Institute of Technology (http://bcit.ca/)
+ * @copyright	Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
  * @license	http://opensource.org/licenses/MIT	MIT License
  * @link	http://codeigniter.com
  * @since	Version 1.0.0