[WIP] Spreadsheet validation

This is associated with moving inappropriate code out of config/settings.yml which is associated with the upload of orphan spreadsheets (https://osraav.atlassian.net/browse/OSRA-240)
I've created this pull request just to provide visibility of the approach I've been taking, to see if you want me to progress along these lines. 
Note that this will cause several rspec failures, because I haven't updated the tests to align with this module design. 
One of the goals here was to lose the fixed spreadsheet column position (eg 'A', 'B', 'C') and replace it with a columns title that would accept both Arabic and English. Could the format be modified to achieve this ?