Improve logging

[sbrudz]

Logging is currently done using console.log. This makes log aggregation challenging and doesn't provide a timestamp or other context to help with interpreting the logs. See https://github.com/i0natan/nodebestpractices/blob/master/sections/errorhandling/usematurelogger.md
for more information.

Switch all logging to use Winston -- https://github.com/winstonjs/winston