Use logging instead of print in codebase

[chanind]

Currently, logging info is output using print(), but this makes it hard to control the verbosity level of the output, and cannot distinguish between debugging / info statements and warnings / errors. For instance, in sae_training/config.py, creating a config object prints a lot of statements, but these are a mix of debugging / info / warnings, and would be better suited to using the Python logging module.

[anthonyduong9]

I can work on this this week.