bridge: added function to calculate bridge wait time

When STP is enabled, the bridge may need up to 50sec
(using defaults) longer to become ready and forward
traffic than without STP and we have to consider this
additional time in timeout calculations.
client-state: Remove stats
schema: Remove unused setState() elements
Merge pull request #356 from pwieczorkiewicz/remove_stats
nanny: Remove statedir when nanny is not in use
Merge pull request #357 from pwieczorkiewicz/remove_statedir

nanny: Remove nanny statedir when nanny is not in use
Update secs during retransmit of dhcp4 packet (bnc#889314)

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Update secs also in offer,renew,rebind

Signed-off-by: Olaf Hering <olaf@aepfle.de>