Webapp detail job submission

This merge request is a major update. It's a fusion between the WebappDetail and JobCreate views alongside their respective templates (and side effects).

The job submission form is now part of the webapp detail. I had to modify the URL endpoints, the WebappDetail has been merged into JobCreate.

Because the webapp detail view is public, I removed the LoginRequired mixin from the view and now check when a job submission is done if the user is identified. If not, an error message is displayed and a log data is stored.

On the template part, the job_add_update.html template has been deleted. The webapp_detail.html is used instead. Three panels are used to display the job submission form, the API documentation and the jupyter notebook if it exists. The job submission form is displayed only to registered users.

A bug fix written by @abaire but signedoff by me has been added in order to take into account anonymous users in the Webapp model because the JobCreate view check who has the right to push or not and anonymous users wasn't a case called for.