added sess_expire_on_close to config file, corrected comment block for session config vars.  Fixes #149
diff --git a/application/config/config.php b/application/config/config.php
index c5eae8f..3f2be48 100644
--- a/application/config/config.php
+++ b/application/config/config.php
@@ -224,15 +224,22 @@
 | Session Variables
 |--------------------------------------------------------------------------
 |
-| 'session_cookie_name' = the name you want for the cookie
-| 'encrypt_sess_cookie' = TRUE/FALSE (boolean).  Whether to encrypt the cookie
-| 'session_expiration'  = the number of SECONDS you want the session to last.
-|  by default sessions last 7200 seconds (two hours).  Set to zero for no expiration.
-| 'time_to_update'		= how many seconds between CI refreshing Session Information
+| 'sess_cookie_name'		= the name you want for the cookie
+| 'sess_expiration'  		= the number of SECONDS you want the session to last.
+|   by default sessions last 7200 seconds (two hours).  Set to zero for no expiration.
+| 'sess_expire_on_close'	= Whether to cause the session to expire automatically
+|   when the browser window is closed
+| 'sess_encrypt_cookie'		= Whether to encrypt the cookie
+| 'sess_use_database'		= Whether to save the session data to a database
+| 'sess_table_name'			= The name of the session database table
+| 'sess_match_ip'			= Whether to match the user's IP address when reading the session data
+| 'sess_match_useragent'	= Whether to match the User Agent when reading the session data
+| 'sess_time_to_update'		= how many seconds between CI refreshing Session Information
 |
 */
 $config['sess_cookie_name']		= 'ci_session';
 $config['sess_expiration']		= 7200;
+$config['sess_expire_on_close']	= FALSE;
 $config['sess_encrypt_cookie']	= FALSE;
 $config['sess_use_database']	= FALSE;
 $config['sess_table_name']		= 'ci_sessions';