Android-Examples: Add KeepScreenOn property to layout of test activity.

jme3-android-examples/src/main/res/layout/activity_test.xml

@@ -8,6 +8,7 @@
                 android:paddingLeft="@dimen/activity_horizontal_margin"
                 android:paddingRight="@dimen/activity_horizontal_margin"
                 android:paddingTop="@dimen/activity_vertical_margin"
+                android:keepScreenOn="true"
                 tools:context="org.jmonkeyengine.jme3androidexamples.TestActivity">
 
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