change remote function invocation from func() to func.remote() (#328)

examples/hyperopt/README.md

@@ -105,7 +105,7 @@ computation. Instead, it simply submits a number of tasks to the scheduler.
 result_refs = []
 for _ in range(100):
   params = generate_random_params()
-  results.append((params, train_cnn_and_compute_accuracy(params, epochs)))
+  results.append((params, train_cnn_and_compute_accuracy.remote(params, epochs)))
 ```
 
 If we wish to wait until the results have all been retrieved, we can retrieve

examples/hyperopt/driver.py

@@ -37,7 +37,7 @@ if __name__ == "__main__":
     dropout = np.random.uniform(0, 1)
     stddev = 10 ** np.random.uniform(-5, 5)
     params = {"learning_rate": learning_rate, "batch_size": batch_size, "dropout": dropout, "stddev": stddev}
-    results.append((params, hyperopt.train_cnn_and_compute_accuracy(params, epochs, train_images, train_labels, validation_images, validation_labels)))
+    results.append((params, hyperopt.train_cnn_and_compute_accuracy.remote(params, epochs, train_images, train_labels, validation_images, validation_labels)))
 
   # Fetch the results of the tasks and print the results.
   for i in range(trials):