CurieBLE: advertising doesn't work with longer local names

Observed by @CarlaMSedze and @rodriguezcarlos from the Arduino CTC team in Malmo.

```arduino
#include

void setup() {
BLE.begin();

BLE.setLocalName("Messenger");

BLE.advertise();
}

void loop() {
}
```

We expect this sketch to work. As with 2.0.2 both the advertisement data and scan response are supported. I think we should be able to support local name values up to 20 characters ....

Start with the CurieBLE sketch using BLE.begin(), BLE.setLocalName("Messenger"), and BLE.advertise(). Check how advertising data and the scan response handle local names, then verify that a 20-character local name works in both supported payloads.

Written by the indexing model from the issue text.