BTRadio: BT re-connection fix + exeptions' msgs  - using service

* BTRadio: BT re-connection problem solved, almost solved :)

The current state of the code is the best I can do now. There are some Android BT stack issues involved here. The solution I used is told to work at about 75% re-connection tests. It seems it does, we can not get more...

to-do: Add a message box to visualize BT stack problems, asking to reboot Drone BT module.