add more mmcls pretrained models (#741)

mmcv/model_zoo/mmcls.json

 {
+  "vgg11": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg11-01ecd97e.pth",
+  "vgg13": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg13-9ad3945d.pth",
+  "vgg16": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg16-91b6d117.pth",
+  "vgg19": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg19-fee352a8.pth",
+  "vgg11_bn": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg11_bn-6fbbbf3f.pth",
+  "vgg13_bn": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg13_bn-4b5f9390.pth",
+  "vgg16_bn": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg16_bn-3ac6d8fd.pth",
+  "vgg19_bn": "https://download.openmmlab.com/mmclassification/v0/imagenet/vgg19_bn-7c058385.pth",
+  "resnet18": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnet18_batch256_20200708-34ab8f90.pth",
+  "resnet34": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnet34_batch256_20200708-32ffb4f7.pth",
+  "resnet50": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnet50_batch256_20200708-cfb998bf.pth",
+  "resnet101": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnet101_batch256_20200708-753f3608.pth",
+  "resnet152": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnet152_batch256_20200708-ec25b1f9.pth",
   "resnet50_v1d": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnetv1d50_batch256_20200708-1ad0ce94.pth",
   "resnet101_v1d": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnetv1d101_batch256_20200708-9cb302ef.pth",
   "resnet152_v1d": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnetv1d152_batch256_20200708-e79cb6a2.pth",
   "resnext50": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnext50_32x4d_batch256_20200708-c07adbb7.pth",
+  "resnext101_32x4d": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnext101_32x4d_batch256_20200708-87f2d1c9.pth",
   "resnext101": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnext101_32x8d_batch256_20200708-1ec34aa7.pth",
   "resnext152": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnext152_32x4d_batch256_20200708-aab5034c.pth",
   "se-resnet50": "https://download.openmmlab.com/mmclassification/v0/imagenet/se-resnet50_batch256_20200804-ae206104.pth",
   "se-resnet101": "https://download.openmmlab.com/mmclassification/v0/imagenet/se-resnet101_batch256_20200804-ba5b51d4.pth",
+  "resnest50": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnest50_converted-1ebf0afe.pth",
+  "resnest101": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnest101_converted-032caa52.pth",
+  "resnest200": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnest200_converted-581a60f2.pth",
+  "resnest269": "https://download.openmmlab.com/mmclassification/v0/imagenet/resnest269_converted-59930960.pth",
   "shufflenet_v1": "https://download.openmmlab.com/mmclassification/v0/imagenet/shufflenet_v1_batch1024_20200804-5d6cec73.pth",
   "shufflenet_v2": "https://download.openmmlab.com/mmclassification/v0/imagenet/shufflenet_v2_batch1024_20200812-5bf4721e.pth",
   "mobilenet_v2": "https://download.openmmlab.com/mmclassification/v0/imagenet/mobilenet_v2_batch256_20200708-3b2dc3af.pth"