Add AppNavigation demo

This demo illustrates the use of the new support library functionality
for navigating within and across tasks using "up" navigation. This
matches the recommendations in the Android design guide.

Change-Id: I2b36c962dd24f0e0f3b3ee3f86319dafc2fc66e2
diff --git a/build/sdk.atree b/build/sdk.atree
index b1b313b..f380cd4 100644
--- a/build/sdk.atree
+++ b/build/sdk.atree
@@ -159,6 +159,7 @@
 development/samples/ActionBarCompat            samples/${PLATFORM_NAME}/ActionBarCompat
 development/samples/AndroidBeamDemo            samples/${PLATFORM_NAME}/AndroidBeamDemo
 development/samples/ApiDemos                   samples/${PLATFORM_NAME}/ApiDemos
+development/samples/AppNavigation              samples/${PLATFORM_NAME}/AppNavigation
 development/samples/BackupRestore              samples/${PLATFORM_NAME}/BackupRestore
 development/samples/BasicGLSurfaceView         samples/${PLATFORM_NAME}/BasicGLSurfaceView
 development/samples/BluetoothChat              samples/${PLATFORM_NAME}/BluetoothChat