FEATURE: Run topology and APN search when interface is reconected

[nadicek]

ofsoftswitch generates event, when a port gets connected and disconected. Controller should listen on these events and:

• teardown all tunnels that were associated with given port
• re-route PDP CTX that were asociated with torn down tunnel
• re-run ICMP topology discovery and APN ARP discovery

source: magic.py

[nadicek]

Handling of EventOFPPortStatus should be added.

example output
EVENT ofp_event->dpset EventOFPPortStatus
DPSET: A port was modified.(datapath id = 000000000000000c, port number = 2)