There was a bug where the frontend was not passing the organization id to the backend, and thus the fetching of the stats failed for organization articles.
This also adds a bit of error handling for `fetch` API
* Add /stats endpoint for articles, opened only to Pro users
* Add analytics to article stats page
* Add stats button to the article page and test stats page
* Fix JS lint issues
* Do not rely on globals
* Use InstantClick to make transitions work in the pro dashboard
* Fix eager loadings and remove unused queries
* Refactor drawChart
* More consistency in naming
* Display correct analytics for organization
