Stablize api, provide backward compatibility and deprecation warning
Hi,
Pytorch Lightning is great and I enjoy the Keras-like standard training routine with the highly customizable pytorch experience.
I do plan to move most of my pytorch models training to PyTorch-lightning but the rapid release this weeks broke my code several time, and maintaining multiple version on different environments is such a headache.
I do appreciate the move to a better api interface ie tng_dataloader vs training_dataloader.
However, I do think it is necessary to provide backward compatibility between minor version update.
I would like to create a pull-request to provide the polyfilling code and corresponding deprecation warning.  The list of changes I observed in these few days are



 tng_dataloader -> training_dataloader




 experiment-> logger



Is there any more things that i can add to the list?