Add Levinson keyboard (#1723)

* Fork lets_split to levinson

Update subproject default

* Update Readme

* Pass LED backlight info from master to slave over serial

keyboards/levinson/config.h

@@ -0,0 +1,31 @@
+/*
+Copyright 2012 Jun Wako <wakojun@gmail.com>
+Copyright 2015 Jack Humbert
+
+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
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#include "config_common.h"
+
+#ifdef SUBPROJECT_rev1
+    #include "rev1/config.h"
+#endif
+#ifdef SUBPROJECT_rev2
+    #include "rev2/config.h"
+#endif
+
+#endif