Add uWS::destroy calls to examples

examples/EchoServer.cpp

@@ -35,4 +35,7 @@ int main() {
             std::cout << "Listening on port " << 9001 << std::endl;
         }
     }).run();
+
+    /* This is needed to properly clear everything */
+    uWS::destroy();
 }

examples/HelloWorld.cpp

@@ -11,4 +11,7 @@ int main() {
 	}).run();
 
 	std::cout << "Failed to listen on port 3000" << std::endl;
+
+        /* This is needed to properly clear everything */
+        uWS::destroy();
 }