omni: add prebuilt store installer apk

Change-Id: I0940faf1f673fffe9526b63bf1e6f3f4598ecdaf
diff --git a/prebuilt/app/Fun/Android.mk b/prebuilt/app/Fun/Android.mk
index 290e255..4c90592 100644
--- a/prebuilt/app/Fun/Android.mk
+++ b/prebuilt/app/Fun/Android.mk
@@ -5,7 +5,7 @@
 LOCAL_SRC_FILES := EggGame.apk
 LOCAL_MODULE_CLASS := APPS
 LOCAL_MODULE_TAGS := optional
-LOCAL_CERTIFICATE := platform
+LOCAL_CERTIFICATE := PRESIGNED
 LOCAL_MODULE_PATH  := $(TARGET_OUT_APPS)
 LOCAL_DEX_PREOPT := false
 include $(BUILD_PREBUILT)