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/system/libraries/Cart.php b/system/libraries/Cart.php
index 72ef5e8..a0fe105 100644
--- a/system/libraries/Cart.php
+++ b/system/libraries/Cart.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
@@ -55,7 +55,7 @@
 	 *
 	 * @var string
 	 */
-	public $product_id_rules	= '\.a-z0-9_-';
+	public $product_id_rules = '\.a-z0-9_-';
 
 	/**
 	 * These are the regular expression rules that we use to validate the product ID and product name
@@ -63,14 +63,14 @@
 	 *
 	 * @var string
 	 */
-	public $product_name_rules	= '\w \-\.\:';
+	public $product_name_rules = '\w \-\.\:';
 
 	/**
 	 * only allow safe product names
 	 *
 	 * @var bool
 	 */
-	public $product_name_safe	= TRUE;
+	public $product_name_safe = TRUE;
 
 	// --------------------------------------------------------------------------
 
@@ -86,7 +86,7 @@
 	 *
 	 * @var array
 	 */
-	protected $_cart_contents	= array();
+	protected $_cart_contents = array();
 
 	/**
 	 * Shopping Class Constructor