test_totem: generic output gradient check style
test_totem: generic output gradient check style

Indentation is now four spaces, dummyClass now conforms to nn Module
interface.

yozw/torch-totem,deepmind/torch-totem,fzvinicius/torch-totem,dm-jrae/torch-totem,GeorgOstrovski/torch-totem,fbesse/torch-totem,mevGDM/torch-totem