Added a function to report download progress of the MNIST data on the first Udacity example. This commit is primarily intended for users with slow internet connections.
Added a function to report download progress of the MNIST data on the first Udacity example. This commit is primarily intended for users with slow internet connections.

tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples,tensorflow/examples