ZMQ: Added zmq source, destination and transport
ZMQ: Make useage of zmq automatic

 * It means if user didn't set --enable-zmq,
   but zmq is installed it will compile with zmq
ZMQ: removed unused zmq_install.sh

 * It doesn't belong to incubator. It needed for travis only.
ZMQ: fixed zmq libs and cflags
ZMQ: Fixed segfault during reader deinit
ZMQ: Followed up 3.6 related changes

 * stats and other headers location
 * transport init_instance instead of init_method
 * GlobalConfig handling
 * LogThreadedDestination insert handling
ZMQ: added libzmq3-dev for travis
ZMQ: removed unused path option and added SCS_ZMQ
ZMQ: fixed source parsing
Merge pull request #87 from lmesz/zmq

ZMQ: Added zmq source, destination and transport