Add setting to hide shutdown message

Also keeps display from lighting up before shutdown,
which reduces distractions, especially at night and
when the sleep timer is used by allowing the
screen to remain dark.

Change-Id: I1c2d1966f6fb9766532adf01e8828876a871857f

apps/settings_list.c

@@ -1956,6 +1956,10 @@ const struct settings_list settings[] = {
                   "sleeptimer on startup", NULL),
     OFFON_SETTING(0, keypress_restarts_sleeptimer, LANG_KEYPRESS_RESTARTS_SLEEP_TIMER, false,
                   "keypress restarts sleeptimer", set_keypress_restarts_sleep_timer),
+
+    OFFON_SETTING(0, show_shutdown_message, LANG_SHOW_SHUTDOWN_MESSAGE, true,
+                  "show shutdown message", NULL),
+
 #ifdef HAVE_TOUCHPAD_SENSITIVITY_SETTING
 /* If specific values are set for touchpad sensitivity setting we use those */
 #if (defined(MAX_TOUCHPAD_SENSITIVITY_SETTING) \