[Kernel] Change the version number to v2.0.1.

include/rtdef.h

 /*
  * File      : rtdef.h
  * This file is part of RT-Thread RTOS
- * COPYRIGHT (C) 2006 - 2012, RT-Thread Development Team
+ * COPYRIGHT (C) 2006 - 2015, RT-Thread Development Team
  *
  *  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
@@ -50,7 +50,7 @@ extern "C" {
 /* RT-Thread version information */
 #define RT_VERSION                      2L              /**< major version number */
 #define RT_SUBVERSION                   0L              /**< minor version number */
-#define RT_REVISION                     0L              /**< revise version number */
+#define RT_REVISION                     1L              /**< revise version number */
 
 /* RT-Thread version */
 #define RTTHREAD_VERSION                ((RT_VERSION * 10000) + \