Provide methods to turn on/off front light, get/set front light level.

You need declare WRITE_SETTINGS permission in the AndroidManifest.xml

`<uses-permission android:name="android.permission.WRITE_SETTINGS" />`

You can see sample code in [FrontLightDemoActivity](../app/src/main/java/com/android/onyx/demo/FrontLightDemoActivity.java)