Assign graph to cpu in example/udacity/assignment5.
Assign graph to cpu in example/udacity/assignment5.

This was required so the code will execute on tensorflow
installations with gpu support. SparseApplyAdagrad op has
no gpu implementation at this time and causes exception to be
thrown.

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