Option to suppress output of every epoch

[adamlmaclean]

Printing loss & epoch number every time loses place in notebook. Can we set the default to print every 50 epochs? And have a parameter to control whether or not to print/how often to print?

[timkartar]

Added an argument to log to a file instead of to STDOUT if one wishes.

[adamlmaclean]

It would still be great to change default # of prints to every 50 epochs rather than every one (in addition to STDOUT)