GATTserver broadcast trainer information + characteristics' descriptions

[Ruggero1912]

The GATT server should broadcast the name of the trainer / the name of the training session, so that the Athlete's client app would show some information useful to select the right training session. Required:

• [ ] broadcast the trainer / training session name

Optional:

• [ ] change the characteristics and services UUID using some of the canonical ones so that those would be recognised correctly
• [ ] add a description for some of the characteristics (?)

[Ruggero1912]

at the moment it is broadcasting the UUID of the ATHLETE_INFORMATION_SERVICE:

AdvertiseData data = new AdvertiseData.Builder()
                .setIncludeDeviceName(true)
                .setIncludeTxPowerLevel(false)
                //TODO: broadcast the trainer name and a right UUID that should be knwown by the client app
                //.addServiceData(new ParcelUuid(AthleteInformationService.ATHLETE_INFORMATION_SERVICE), "trainerApp".getBytes(StandardCharsets.UTF_8))
                .addServiceUuid(new ParcelUuid(AthleteInformationService.ATHLETE_INFORMATION_SERVICE))
                //FENOM: TODO: add service UUID here (ma vanno aggiunti gli UUID di tutti i service o solo di uno basta?)
                .build();

It could be useful to broadcast also the name of the trainer, but not mandatory IMO