nanny: change calloc() to xcalloc()
nanny: Do not update <client-into> and client-state> by default

Update only when new policy is to be applied by nanny
(device is explicitly enabled). Thus nanny update states
when it is responsible for configuration, and does not
update when ifup is doing it's job.
Merge pull request #176 from pwieczorkiewicz/nanny-client-info