autopep8
protecting archived experiments from data loss

actions that delete data should be prohibited on archived experiments.
at some point will need to build better archival workflows including conversion to more durable data formats
Adding tests for Experiment Session Singup
Fixes #6
Getting rid of hardcoded urls in templates and tests for subjectpool
refactoring check_user_email, adding test stubs
fixing tests
refactoring vcweb json response usage, resolves #7