Renames keyboard folder to keyboards, adds couple of tmk's fixes (#432)

* fixes from tmk's repo

* rename keyboard to keyboards

keyboards/arrow_pad/arrow_pad.h

@@ -0,0 +1,18 @@
+#ifndef ARROW_PAD_H
+#define ARROW_PAD_H
+
+#include "matrix.h"
+#include "keymap.h"
+#ifdef BACKLIGHT_ENABLE
+	#include "backlight.h"
+#endif
+#include <avr/io.h>
+#include <stddef.h>
+
+void matrix_init_user(void);
+void matrix_scan_user(void);
+bool process_action_user(keyrecord_t *record);
+void led_set_user(uint8_t usb_led);
+void backlight_init_ports(void);
+
+#endif