Update of job process [was: Reading of Redis logs for a specific job]

This merge request has been changed quite a lot as there were several commits/files missing.

The main changes added are on the job part. Nevertheless, a prior cleaning and update of the code documentation has been performed on both views.py and urls.py files.

Then to take into account the comments, the job detail view has been modified to take into account the status of the job to display either the Redis log data (NEW or RUNNING status) or the job log file located in the datastore.

On the job creation part, it's now possible to select pre recorded presets coming from the WebappParameter model.

I finally merged the django branch in order to take the modifications introduced by @abaire regarding the webapp version management.

[merge request description archived]

I added a helper function to extract the job logs for a specific job in the Redis database. The function is a copy of another part of the code not merged yet in the master branch.

I updated the view accordingly, added a proper docstring and moved the class in the module to keep the code ordered. I updated as well the template to display the data.