EBI Code - Ready for review/merge 🍻

For review.  As we discussed, getting EBI submission working without having to go through qiita_pet is the priority.  Therefore, this is the code that currently exists for generating ```EBISubmission``` objects.  Test code is not complete and @teravest could use some help!  If you can help with test code, please make PRs against my branch (ebi-issue-314).