Missing options for SetSockOpt

There are some zmq options I couldn't find any mentions of those in [binding.cc](https://github.com/JustinTulloss/zeromq.node/blob/7dabf27bc95ec7715b0da4bc2687b5c5ea76b8c9/binding.cc).
Here is a list of those comparing to zmq 3.0 ( http://api.zeromq.org/3-0:zmq-setsockopt ):
- ZMQ_RECONNECT_IVL_MAX
- ZMQ_MAXMSGSIZE
- ZMQ_MULTICAST_HOPS
- ZMQ_RCVTIMEO
- ZMQ_SNDTIMEO

and additionally comparing to zmq 3.2 ( http://api.zeromq.org/3-2:zmq-setsockopt ):
- ZMQ_IPV4ONLY
- ZMQ_DELAY_ATTACH_ON_CONNECT
- ZMQ_ROUTER_MANDATORY
- ZMQ_XPUB_VERBOSE
- ZMQ_TCP_KEEPALIVE
- ZMQ_TCP_KEEPALIVE_IDLE
- ZMQ_TCP_KEEPALIVE_CNT
- ZMQ_TCP_KEEPALIVE_INTVL
- ZMQ_TCP_ACCEPT_FILTER

I wonder if adding these options will automatically enable the features. I'm not a c++ guy but as far as I can see constants like ZMQ_IDENTITY are just defined and forwarded into zmq core.