680: Added new loss functions. r=thebhatman a=thebhatman
I have added the KL Divergence Loss function, Poisson loss function, Logcosh loss, and Hinge loss function.
Co-authored-by: Manjunath Bhat <manjunathbhat9920@gmail.com>
Co-authored-by: thebhatman <manjunathbhat9920@gmail.com>