#3 FadaLeaseRenewer is late renewing

[Juanjo Aparicio Jara]

The FadaLeaseRenewer class has a thread to schedule
lease renewals. However, the renewal itself is
performed in that thread. If a lease renewal takes
enough time, the renewal of the next lease will be
late. As a consequence, some services are lost, and
need to be registered again. This increases the traffic
generated, and causes service disruption.

The lease renewal action should be performed in a
separate thread. This separate thread should also
update the lease queue.