fix for issue 52: cpu mode epochs

[TTN-]

Applying fix for issues:
#52
#75

[TTN-]

EDIT: ignore that last commit for now, its semi broken.

I've just added one more commit to my fork, not sure if you'd like to have it in yours too.
I find that the --dataset size parameter isn't listened to at all if the dataset has already been generated. So if I run it once with --dataset 1000, then later again with --dataset 80000 later, I will still actually be using the 1000 dataset. Generating the dataset takes only a fraction of the time needed to train a network, so it is easiest to fix this by simply generating the dataset on each run as a workaround. Like I said maybe you dont want to include it here, but its there if you like it..
Just want to say though, this project is amazing, I'm toying around with it a lot. Very interesting to test on.