THRIFT-4571: Updated ZeroMQ examples to ZeroMQ version >= 3.0. (#1556)

* New style for Python is default now.
* Symbols were replaced in newer versions of ZeroMQ (>=3.0).
* Use Thrift's abstraction for `shared_ptr` instead of Boost.
* Symbols were replaced in Python as well.
diff --git a/contrib/zeromq/TZmqServer.h b/contrib/zeromq/TZmqServer.h
index a840c86..43f86c0 100644
--- a/contrib/zeromq/TZmqServer.h
+++ b/contrib/zeromq/TZmqServer.h
@@ -28,7 +28,7 @@
 class TZmqServer : public TServer {
  public:
   TZmqServer(
-      boost::shared_ptr<TProcessor> processor,
+      apache::thrift::stdcxx::shared_ptr<TProcessor> processor,
       zmq::context_t& ctx, const std::string& endpoint, int type)
     : TServer(processor)
     , processor_(processor)
@@ -56,7 +56,7 @@
   }
 
  private:
-  boost::shared_ptr<TProcessor> processor_;
+  apache::thrift::stdcxx::shared_ptr<TProcessor> processor_;
   int zmq_type_;
   zmq::socket_t sock_;
 };