Add a function `extract_job_zip`

[micheles]

It must work for Aristotle calculations. It must export a job.zip archive (only for GEM users) containing:

1. job.ini
2. rupture.csv
3. gsim_lt.xml
4. site_model.csv
5. exposure.xml and exposure.csv
6. vulnerability functions.xml
7. taxonomy_mapping.csv

This is a lot of work, but the hard part is checking that indeed by running the job.zip one can recover the results of the original Aristotle calculation. As a second step it should be extended to all situations including:

no	kind of calculation
1	normal xml rupture
2	rupture_dict
3	shakemap_uri
4	ruptures_file
5	gmfs_file
6	hazard_curves_file
7	exposure.hdf5 + normal rupt
8	exposure.hdf5 + rupture_dict
9	exposure.hdf5 + shakemap_id