I'd like to rename a few things (in the tests too) : 

* `BTButton` -> `bluetoothButton`
* `BTMenu` -> `bluetoothMenu`
* `BTMenuBTButton` -> `switchToDeviceButton`
* `BTMenuReceiverButton` -> `switchToReceiverButton`
* `BTMEnuSpeakerButton` -> `switchToSpeakerButton`