update import_task
Merge branch 'validation' of github.com:afimb/chouette2 into validation
Merge branch 'validation' of github.com:afimb/chouette2 into validation
Merge branch 'validation' of github.com:afimb/chouette2 into validation
Merge branch 'validation' of github.com:afimb/chouette2 into validation
merged
Merge branch 'validation' of github.com:afimb/chouette2 into validation
preserve JSON fields on update_attribute