remove one_hot, first try

Here in line 127, calling the super() in this way changes d.y slightly. In the previous version, d.y is initialized as a vector (i.e., of shape (2,) for the test dataeset.), after the modification, it is now initializing d.y to be a 2-d ndarray (of shape (2, 1) for the test dataset). 

Should I change the test file accordingly? Or it will yield test failures.