added printing status and tests for it

[mnoukhov]

Printing extension had default print_status=True without the ability to change it, I'm just adding it as a an argument.

Also added tests to a new test_printing.py, I found there was a printing test in test_progressbar but that felt more like a integration test than a unit test for something so simple as the print_status argument.

[rizar]

Sorry for the late reply and thanks for the PR! I am a bit hesitant to merge it though. There is so many ways in which Printing could be customized, and it would never fit everybody's needs. This is why we have been keeping it primitive as it is so far.

[mnoukhov]

That makes sense, but the code already has just an unused variable print_status that is just never set. This change makes it usable and adds the ability to make normal runs (that don't need the status, which I imagine would be the majority) much cleaner.

[rizar]

I think most people prefer to print status, because without printing it one doesn't even know how many iterations of training have been done.