[Bug fix]Data Parallel issue with types.MethodType

[wpwei]

Problems / Bugs

1. Data Parallel issue with types.MethodType Data Parallel issue with types.MethodType #112
2. The 'num_classes' is not passed to torchvision models. All models are initiated for 1000 classes even if num_classes parameter is set to other numbers. It is confusing when using this interface with torchvision models from scratch.

Fix

1. Rewrite the classes for torchvision model.
2. Simply pass the 'num_classes' to torchvision.models interface will fix it.