Some fixme in bluetooth.c

Thanks for the feedback, each information is its own step for my (hopefully better) understanding.
There is a function deep inside Bluetooth stack sources, which might help.
For now I bypass the data from jswrap_nrf_bluetooth_getAdvertisingData and use the API-Call which takes a structure to set ADV data.
At least for first examples it works.
Next step will be how to handle readable and writeable for char and descriptors