Make hello world more visual (#176)

It was noted in the DX studies that users tend to miss hello world run since it is so short. So adding a for loop to make it more noticeable.
For now, only making this change to c++. Once we confirm that this idea works in subsequent tests, we can make the change to other samples.

Author: anjgola

hello-world/cpp/main.cpp

@@ -26,8 +26,10 @@
 
 int main()
 {
-    std::cout<< "Hello, Internet of Things!" << std::endl;
-    sleep(1);
+    for (int i =0; i<5 ; i++) {
+        std::cout<< "Hello, Internet of Things!" << std::endl;
+        sleep(1);
+    }
     std::cout<< "Bye!" << std::endl;
     return 0;
 }