Merge nightstand_clock from https://github.com/xMasterX/all-the-plugins

nightstand_clock/clock_app.c

@@ -4,6 +4,7 @@
 #include <gui/gui.h>
 #include <gui/elements.h>
 
+#include <notification/notification.h>
 #include <notification/notification_messages.h>
 #include <notification/notification_app.h>