Add CW attack

1. Add CW L2 and Linf attack
2. Add example code for CW attack

Update FGMT

1. Fix bug in #6, should use dynamic batch size
2. Add example for fgmt random target and default target

Update DeepFool

1. deepfool returns noise only when noise=True
2. fix few typos in DeepFool examples
3. Add DeepFool noise example

Update DeepFool

1. Bug fix for DeepFool binary classifier case
2. Add batch mode for DeepFool where the algorithm runs until the max epoch is reached.
3. Add batch mode example

Initial release with citation

1. FGM, JSMA, and DeepFool are implemented
2. All examples are based on MNIST.