Ok, so I think that the modifications I made here can be merged ...
Two main changes as compared to the master:
Change 1 should by no means affect what has been done until now (on the master). However, change 2 may require a bit of adaptation, especially when defining architectures and layers ...
@tiago.pereira I'll let you check and then we can discuss
Also, I think that this will be irrelevant when we'll go to tf-slim anyway !