OVSDriver: replace buggy ind_ovs_port_find with ind_ovs_port_lookup_by_name
OVSDriver: watch NETLINK_ROUTE for link state changes

The vport multicast group does not get notified when the link state changes. We
have to use another netlink family to get these notifications.
OVSDriver: populate port desc state field

Fixes XE-22
OVSDriver: save interface flags in struct ind_ovs_port

Needed for the next commit. Also reduces the number of ioctls we need to do.
OVSDriver: log when an interface transitions between up/down

Fixes XE-41
OVSDriver: clean up indigo_port_stats_get

Now does a netlink GET instead of DUMP when getting stats for a single port,
and doesn't use a nested function to fix the clang build.
OVSDriver: get stats from linux interface when possible

The datapath port stats are more limited.

Fixes XE-21, XE-45
debian: fix libnl-genl-3-dev dependency for oneiric
Merge into master from pull request #1:
Port subsystem bugfixes (https://github.com/floodlight/ivs/pull/1)