Add Teensy2 Atreus support

keyboard/atreus/atreus.c

@@ -0,0 +1,29 @@
+#include "atreus.h"
+
+__attribute__ ((weak))
+void * matrix_init_user(void) {
+	// leave these blank
+};
+
+__attribute__ ((weak))
+void * matrix_scan_user(void) {
+	// leave these blank
+};
+
+void * matrix_init_kb(void) {
+	// put your keyboard start-up code here
+	// runs once when the firmware starts up
+
+	if (matrix_init_user) {
+		(*matrix_init_user)();
+	}
+};
+
+void * matrix_scan_kb(void) {
+	// put your looping keyboard code here
+	// runs every cycle (a lot)
+
+	if (matrix_scan_user) {
+		(*matrix_scan_user)();
+	}
+};