Non blocking init

With this release the BLE scan function which is started with the hub.init() call is no longer blocking the execution of the code. Now a callback is used and with this the non blocking way of scanning is enforced in the NimBLE-Arduino library.

Thanks to @bjgz and @fvanroie for pointing me in the right direction

To use this feature you have nothing to do 😃 beside the update of the library to this version