switch project to dev mode
1 It appears that there is no site:mode command in the latest drupal console (1.0.0-rc16), but instead site:maintenance (sma) (on/off) is available. Maybe they ditched site:mode at some point because site:maintenance made more sense in Drupal context.

2 Make sure you have this code in development.services.yml:

services:
  cache.backend.null:
    class: Drupal\Core\Cache\NullBackendFactory