Reproduce MobileNetV3 using gluon interface of mxnet
paper: https://arxiv.org/pdf/1905.02244.pdf
paper small: top1 is 67.4, #params 2.9M
our small: top1 is 67.79, top5 is 87.53, #params 2.82M
paper small-0.75: top1 is 65.4, #params 2.4M
our small-0.75: top1 is 64.24, top5 is 84.84, #params 2.27M
paper large: top1 is 75.2, #params 5.4M
our large: top1 is 74.19, top5 is 91.83, #params 4.87M
paper large-0.75: top1 is 73.3, #params 4.0M
our large-0.75: top1 is 71.51, top5 is 90.05, #params 3.5M