Added test_costFunctionReg to ex2 tests

Here's an addition to your unit tests so the entire assignment is now covered.  One caveat:  the expected `logical()` values in your original test_predict.m were causing my tests to fail, so I removed them.  (Maybe you did an element-wise  logical operator to transform your predictions to 0, 1 values?  I used `round( sigmoid( X*theta))` to generate that matrix)  So... I think applying my pull request might break your tests; apologies.

Thanks for putting this project up!