Make example for new BLE features like background scanning etc

[ghost]

Users have requested an example app that demonstrates BLE scanning and background
notifications (using the local notification plugin). In issue:

https://github.com/evothings/evothings-planning/issues/130

....several other new features are planned like different ways to auto connect, not only by device name, also by services and more.

For example, when the app is in the background and detects a particular BLE device, it creates a notification. We could make a similar example also for the iBeacon plugin.