#86 Fix SendHello/ReceiveHello examples

[Bernd Löhr]

SendHello and ReceiveHello example applications currently do not match, as one would expect. They should run right out of the box.

[Bernd Löhr]

sendHello is modified to correctly handle data transmissions:

• if no data argument is given: transmit "Hello World"
• if data argument has size > 0: transmit given data
• if data argument is empty: transmit "Just a Counter: nnnn"