Recovery: Add support in lk to read/write recovery messages.

Add support in bootloader to intract with recovery code.
diff --git a/app/aboot/rules.mk b/app/aboot/rules.mk
index e133257..c23784e 100644
--- a/app/aboot/rules.mk
+++ b/app/aboot/rules.mk
@@ -2,5 +2,6 @@
 
 OBJS += \
 	$(LOCAL_DIR)/aboot.o \
-	$(LOCAL_DIR)/fastboot.o
+	$(LOCAL_DIR)/fastboot.o \
+	$(LOCAL_DIR)/recovery.o