Homing alarm upon no switch. Licensing update.

- Homing cycle failure reports alarm feedback when the homing cycle is
exited via a reset, interrupted by a safety door switch, or does not
find the limit switch.

- Homing cycle bug fix when not finding the limit switch. It would just
idle before, but now will exit with an alarm.

- Licensing update. Corrected licensing according to lawyer
recommendations. Removed references to other Grbl versions.

grbl/config.h

@@ -1,8 +1,9 @@
 /*
   config.h - compile time configuration
-  Part of Grbl v0.9
+  Part of Grbl
 
-  Copyright (c) 2013-2015 Sungeun K. Jeon
+  Copyright (c) 2012-2015 Sungeun K. Jeon
+  Copyright (c) 2009-2011 Simen Svale Skogsrud
 
   Grbl is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -17,12 +18,6 @@
   You should have received a copy of the GNU General Public License
   along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
 */
-/* 
-  This file is based on work from Grbl v0.8, distributed under the 
-  terms of the MIT-license. See COPYING for more details.  
-    Copyright (c) 2009-2011 Simen Svale Skogsrud
-    Copyright (c) 2011-2013 Sungeun K. Jeon
-*/  
   
 // This file contains compile-time configurations for Grbl's internal system. For the most part,
 // users will not need to directly modify these, but they are here for specific needs, i.e.