Complete task 1 of estimating the mean and variance of the features.
Complete task 2. Make predictions based on epsilon, calculate accuracy
of predictions by finding F number. This allows the rest of the code
to find the best value of epsilon.
Complete task 3. Calculate collabarative filtering cost.
Complete task 4 and 5. Collaborative filtering gradient (no regularization)
and collabarative filtering cost with regularization.
Complete task 6. Add regularization for Theta and X.