Implemented the LightBlue Bean Serial Message Protocal for receiving serial messages.

Currently it assumes that the GT packets are received in order and that they all belong to the same GST.
This can probably be improved upon by checking the Message Count and Packet Count of the GT Header and assembling them in the correct order.

The signature of the Serial message callback has changed.

The complete GST message will be returned on an 'invalid' callback if the CRC fails.