Allow image labels in Torch
Allow image labels in Torch

Labels were restricted to scalars (classification) or vectors (regression).
This change extends supported label types to anything that fits in an LMDB.
Small refactoring of datum decoding.

TimZaman/DIGITS,TimZaman/DIGITS,ethantang95/DIGITS,ethantang95/DIGITS-GAN,TimZaman/DIGITS,gheinrich/DIGITS-GAN,gheinrich/DIGITS-GAN,Deepomatic/DIGITS,Deepomatic/DIGITS,ethantang95/DIGITS,Deepomatic/DIGITS,ethantang95/DIGITS-GAN,bygreencn/DIGITS,gheinrich/DIGITS-GAN,ethantang95/DIGITS,TimZaman/DIGITS,ethantang95/DIGITS-GAN,bygreencn/DIGITS,Deepomatic/DIGITS,bygreencn/DIGITS,gheinrich/DIGITS-GAN,ethantang95/DIGITS,bygreencn/DIGITS,ethantang95/DIGITS-GAN