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/Makefile b/contrib/zeromq/Makefile
index b09f4ee..ee398e2 100644
--- a/contrib/zeromq/Makefile
+++ b/contrib/zeromq/Makefile
@@ -26,7 +26,7 @@
 
 storage/__init__.py: storage.thrift
 	$(RM) $(dir $@)
-	$(THRIFT) --gen py:newstyle $<
+	$(THRIFT) --gen py $<
 	mv gen-py/$(dir $@) .
 
 $(GENSRCS): storage.thrift