Add epoch counter for better tracking for train/test cycles

[RyanHope]

[matthiasplappert]

What is the concept of an epoch vs. an episode here?

[RyanHope]

Sorry I am just getting back to this. One epoch is one train/test cycle, it's a concept used widely throughout the machine learning community. Right now every time fit() is called the episode count is reset which is annoying if you are trying to get a true count of how many episodes were run if fit() is called multiple times.

The concept of an epoch would also allow for annealing the learning parameters after N epochs instead of after N episodes.