Add unique constraint on study.study_title

We should not allow multiple studies with the same title, and we can use this
for the exists method of the Study class
Add test for exists, fix tests that violted unique

Some tests used to create studies that had the same name as the test study;
I changed the tests so that the study created inside the test has a slightly
different study_title than the study created in the populate_test_data.sql
script
Fix bug with emails and addresses

JS Function call was passing wrong value for address, and was instead
replicating the email address
Change processing mode, update code to reflect