Add Android.mk files for the Notepad tutorial's solutions

Now the tutorial is built as part of the standard build, but not installed
as part of the system image.  Required localizing an android:text field
that was already localized in Notepadv1 but for some odd reason was no
longer localized in v2 and v3.

Change-Id: I0e1b41a4efa454a503b788b0698593136662a014

tutorials/NotepadCodeLab/Notepadv2Solution/res/layout/notes_list.xml

@@ -9,5 +9,5 @@
   	<TextView android:id="@+id/android:empty"
           android:layout_width="wrap_content"
         	android:layout_height="wrap_content"
-        	android:text="No Notes!"/>
+        	android:text="@string/no_notes"/>
 </LinearLayout>