Add Android framework api 15
Add Android framework api 15

Summary:
```
dx --core-library --dex --output /tmp/class-15.dex /opt/android_sdk/platforms/android-15/android.jar
./tools/python/dex.py --dump-structure --public-only --use-bytecode-format /tmp/class-15.dex > service/api-levels/framework_classes_api_15.txt
echo -en "\x00" >> service/api-levels/framework_classes_api_15.txt
```

Reviewed By: emma0303

Differential Revision: D22250632

fbshipit-source-id: 9d8ad99bcfc6c088cc8cec08d19cc66f55bf53e2

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