Consider adding a new console logger with INFO level

[jmaupetit]

Purpose

As discussed with @mbenadda [1] some relevant logs may get lost if we only use sentry for logs with a level >= WARNING.

Proposal

Add a new logger using the console handler with the INFO level so that we can store and use them at a system level depending on the infrastructure (e.g. OpenShift + ELK).

Reference(s)

[1] https://github.com/openfun/richie/pull/112#discussion_r185534415

[sveetch]

As discussed today from Slack with @jmaupetit and @mbenadda , it seems log ouptut is totally muted in local development, particularly from CLI commands like bootstrap_elasticsearch.

This would be nice to have logger config for local development to have logger correctly enabled so we can use logger.info() and even logger.debug() inside commands.