Add checkNNGradients.m

Function to help check gradients
Revert "Add checkNNGradients.m"

This reverts commit 6cadd0f1eeb134caf9e5ffda70cf122edf6ee26c.
Add ex4.m

Octave script that will help check the result of exercise
Add ex4data1.mat

Training set of hand-written digits
Add ex4weights.mat

Neural network parameters for exercise 4
Add checkNNGradients.m

Function to help check gradients
Add computeNumericalGradient.m

Numerically compute gradients
Add debugInitializeWeights.m

Function for initializing weights