Re-enable bluetooth

[calin-iorgulescu]

There are 2 issues that need fixing:

• When calling 'new CargoClient()', the applicationPlatformProvider cannot be null. Just creating a dummy class that extends IApplicationPlatformProvider with no functionality seems to be enough.
• Modifying deviceTransportApp of CargoClient is no longer possible. However, it seems that this property now just reads runningFirmwareApp from BandClient. Simply making the BandClient.runningFirmwareApp field public in bootstrap, and changing it after creating the new CargoClient is enough to make things work again.