Add users

migrations/002_emails_are_unique_for_user.sql

@@ -0,0 +1,10 @@
+-- Write your migrate up statements here
+create unique index users_unique_index
+on users(email);
+
+---- create above / drop below ----
+
+drop index users_unique_index;
+
+-- Write your migrate down statements here. If this migration is irreversible
+-- Then delete the separator line above.