mattdrayer: Change model fieldname, revise code, fix bad tests.

We need to be able to track which site a given user account was created on. This
change will create a UserAttribute model with a key of 'created_on_site' and a value
containing the domain of the site on which the user accounted was created.

WL-977

We should not be using custom signing keys for each service at this time. We may want to return to this strategy in the future; but, this is not the direction any of our other services are going in.

ECOM-6541

ECOM-2361

Make escaping for json simpler and more consistent in Mako templates
- add escape_json_dumps to escape and json.dumps
- add escape_js_str to escape javascript string
- refactor Studio to use escape_json_dumps in Mako templates

TNL-2646: Escape json.dumps

ECOM-2044

PR #8930

ECOM-1017

* Add a new cookie for user information
* Make marketing cookie names configurable.
* Handle URL reversal when URLs don't exist (in Studio)
* Move cookie code from student/helpers.py into its own module.

TNL-2024

TNL-1535

Makes logistration available at /login and /register as well as /accounts/login/ and /accounts/register/. In addition:

- Adds support for redirect URLs in third party auth for combined login/registration page
- Adds support for external auth on the combined login/registration page
- Removes old login and registration acceptance tests
- Adds deprecation warnings to old login and register views
- Moves third party auth util to student_account
- Adds exception for microsites (theming)

* updating vendor files
* updating class syntax (to new FA-based classes) for all UI elements
* correcting broken tests