Rewrite attachment validator to avoid validating every file once for every submitter role

Validating all attachments one time for every role a submitter has is a waste of resources. Figure out the values for the file validators before we call file_save_upload() to validate the files. This basically means moving the call to file_save_upload() out of the foreach loop for roles, and making the process of figuring out the values of the validators a little more clever.