* added generate certificates task and bok choy tests
* added unit tests
* changes based feedback and improved acceptance test
* Change header text
* changes based on feedback on 24/6
* added task_id to api output
* fixed broken test
* Remove "Instructor" from strings, per Docs team
* Fixed flaky entrance exam test
some optimisations
refactored code and added created event
added test to make sure generate event is emitted
changes based on feedback on 6/11
added certificate web page and tests
fixed quality violations
