Merge pull request #46 from cmdevries/master

Fix crash on sending a std::string larger than 2GB
Add some method to the poller that allows to use zmq_pollitem_t directly
Reactor class; We can register socket or fd and have callback called when watched events occur.
Simple tests
Add method remove(zmq_pollitem_t) to poller
Merge pull request #47 from xaqq/zmq-reactor

Zmq reactor
This fixes a bug in zmqpp::reactor that occured when calling remove() from a handler.
Merge pull request #48 from xaqq/zmq_reactor_fix_remove

Bug in zmqpp::reactor
Adds zmqpp::actor, this class is similar to CZMQ zactor, that is it provide an easy way to spawn a thread an to communicate with it. Adds a zmqpp::signal enumeration that is used to send signal to socket (for interthread synchronization). zmqpp::socket and zmqpp::message have new methods to deal with zmqpp::signal
Merge pull request #51 from xaqq/actor_pr

zmqpp::actor
Enable unbind and disconnect methods for class socket only for ZMQ >= 3.2
Merge pull request #52 from xdmiodz/develop

Enable unbind and disconnect methods for class socket only for ZMQ >= 3.2