Indenting police
Rework net, worker and some http internals.

- The net code no longer has a recv_queue, instead reuse same recv buffer.
- Introduce net_recv_reset() to reset the recv buffer when needed.
- Have the workers spread the load better between them by slightly
  delaying their next accept lock and giving them an accept treshold
  so they don't go ahead and keep accepting connections if they end
  up winning the race constantly between the workers.
- The kore_worker_acceptlock_release() is no longer available.

- Prepopulate the HTTP server response header that is added to each
  response in both normal HTTP and SPDY modes.
- The path and host members of http_request are now allocated on the heap.

These changes overall result better performance on a multicore machine,
especially the worker load changes shine through.