This reverts commit a517dc20.

When registering for an verified certificate, if you selected a suggested price option, closed the browser halfway through the steps, and re-opened, the contribution would be written in the text input field instead of preselecting the appropriate radio button.  This commit fixes that behavior

add middleware to detect students with disabled accounts

add tests

add migration

This reverts commit ec01253e, reversing
changes made to ae8c9710.

By transparently proxying between the XModuleDescriptor and the XModule,
and between their runtimes, we can make them act as a single class, so
that we can swap in an actual XBlock instead.

as a first step to separating db connection from modeling
and to support location mapper and contentstore using same db config as modulestore

Authenticate to the database before getting a reference to the
collection.

Fixed grading tests

With tests, some settings changes
(all should default to not breaking anything for edx)

Added styling for shopping cart User Experience
- Styled shoppingcart list page
- Styled navigation shopping cart button
- Styled receipt page
- Styled course about page for shopping cart courses

Addressed HTML/SCSS issues

Remove offending body class and unnecessary sass changes

Addresses many review comments on stanford shopping cart

* framework for generating order instructions on receipt page
  in shoppingcart.models
* move user_cart_has_item into shoppingcart.models
* move min_course_price_for_currency into course_modes.models
* remove auto activation on purchase
* 2-space indents in templates
* etc

revert indentation on navigation.html for ease of review

pep8 pylint

move logging/error handling from shoppingcart view to model

Addressing @dave changes

Also, deletes some unused code.