Http Server: Add routes API

This patch adds an api for the ip route table.
A call to:
http://localhost:8000/network/route/
returns a list of the available routes.

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
bsd: change zfs rwlock implementation to use OSv's rwlock instead of mutex

Gleb explains:

  This is needed for common sense. I do not see improvement with
  Cassandra unfortunately.

Signed-off-by: Gleb Natapov <gleb@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>