See if script select_subject.py still usefull

[sandrinebedard]

select_subjects returns a .yml list of all subjects to include in the analysis (the subjects that are missing a field are exluded). Not a lot of subjets are missing a selected field in the dataset, won't change a lot to still process images of those subjects and could be useful for another project, and they are already excluded from the statistical analysis. I propose to remove this script, it is not used right now.