"Packet too big" during BLE connection request on BBC Microbit, RFDui… (#463)
"Packet too big" during BLE connection request on BBC Microbit, RFDui… (#463)

* "Packet too big" during BLE connection request on BBC Microbit, RFDuino, nRF51822, ...

Problem:
When using BLE on boards using the library arduino-BLEPeripheral, the Blynk connection request nearly always fails with the message "Packet too big". 

Following boards are using the library arduino-BLEPeripheral:
- BBC Microbit 
- RF Duino BLE
- RedBearLab nRF51822
- and other nRF51822 based boards
- nRF8001 based boards

Cause
The main cause of this problem is the size of the receiving buffer, which was only 20 bytes. 
Other Blynk implementations of BLE boards however have a receiving buffer size of 512 bytes.

Changes: fix buffer size bug & make the code more in line with other Blynk BLE implementations:
- Receiving buffer size increased
- Change service UUID from Nordic UART to Blynk UUID
- Remove unnecessary advertisement data (name descriptors) to make advertisement data smaller
- Change BLE mode from "Write no response" to "write"
- Removed unnecessary source code, mainly debug info

* BLEPeripheral : onConnect & onDisconnect handling

* duplicate functions rxcount & available

blynkkk/blynk-library,blynkkk/blynk-library,blynkkk/blynk-library,blynkkk/blynk-library,blynkkk/blynk-library