https://www.arduino.cc/en/Reference/BLECharacteristicConstructor claims a `maxLen` parameter but a look at the source of the library ([BLETypedCharacteristics.h](https://github.com/01org/corelibs-arduino101/blob/master/libraries/CurieBLE/src/BLETypedCharacteristics.h)) shows it doesn't exist. Originally reported at http://forum.arduino.cc/index.php?topic=489026