string workround. need NDArray GetNDArrays(NDArray) to implemented.

test/TensorFlowNET.Examples/HelloWorld.cs

@@ -29,9 +29,8 @@ namespace TensorFlowNET.Examples
             {
                 // Run the op
                 var result = sess.run(hello);
-                string result_string = string.Join("", result.GetData<char>());
-                Console.WriteLine(result_string);
-                return result_string.Equals(str);
+                Console.WriteLine(result.ToString());
+                return result.ToString().Equals(str);
             });
         }