Leave device management screen inaccessible for now.

// FREEBIE

res/xml/preferences.xml

@@ -21,11 +21,11 @@
                 android:title="@string/preferences__delete_old_messages"
                 android:icon="?pref_ic_storage"/>
 
-    <Preference android:key="preference_category_devices"
-                android:title="Devices"
-                android:icon="?pref_ic_devices">
+    <!--<Preference android:key="preference_category_devices"-->
+                <!--android:title="Devices"-->
+                <!--android:icon="?pref_ic_devices">-->
 
-    </Preference>
+    <!--</Preference>-->
 
     <Preference android:key="preference_category_advanced"
                 android:title="@string/preferences__advanced"