UsresController#update. Redirects user to classroom after completing their singup.
add classroom_id to url
add hidden field tag for redirect when completing signup
redirect to classroom when student completes signup
studentscontroller#create
Features spec - adding students and send email
StudentsController#create
Tests that students are created in the db and added to the appropriate classroom.
Add database_cleaner gem to delete the test_db after every spec.
Problem was that when using selenium, it created a bunch of objects in the test_db that weren't getting deleted.
database_cleaner assures that the objects in the test db get wipped out after every spec.