I updated the API in order to manage jobs.
Now the GET and POST http commands are available to select and create
jobs for a given user (on `jobs/` endpoint).
The GET and DELETE http commands are available to select a given job for
a given user on `jobs/<id>` endpoint.

I updated the `settings.py` file I added two variables to have
informations related to the datastore directory and the directory name
that will host the jobs files. The current setup is
`/vol/rw/datastore/jobs/<job_id>`.

Signed-off-by: Matthieu Berjon <matthieu.berjon@inria.fr>