Delayed auto-reroute mechanism.

Add the possibility to delay auto reroute mechanism.
Desired delay is configurable using the property ncl.autoreroute.delay in
org.opennaas.extensions.ofertie.ncl.cfg platform configuration file.

Statistics poller default time has been increased to avoid congestion detection when auto-reroute is pending.
Merge pull request #920 from isartcanyameres/demo/delayed-autoreroute

Delayed auto-reroute mechanism.