✨ Feature: write stats to Kibana

In support of User Story: https://github.com/troupe/gitter-webapp/issues/1995

This PR does several things:

Removes the console logger Adds a winston logger Adds a stats provider to log to the winston logger

What does this give us?

When a stat.event is fired, the winston logger will write the event (with metadata) to Kibana.

The log entry can then be cut up further in Kibana and used for reporting.