Optimiser: Implement AMSGrad and Padam
Seems like there is a new optimiser to supplant Adam called AMSGrad and introduced at ICLR 2018.

Paper: https://openreview.net/pdf?id=ryQu7f-RZ


Also Padam from "Closing the Generalization Gap of Adaptive Gradient Methods in Training Deep Neural Networks"
  https://arxiv.org/pdf/1806.06763.pdf