* clean up one last typo

LMS-1387

* make `user_status` more intelligent
* remove some logic from the templates
* rename `parse_error_msg` to `parsed_error_msg`
* fix up and add more tests

LMS-1387

Also includes some tests

Story: LMS-1127

Also includes some tests

Story: LMS-1127

student.views.confirm_email_change: commit/rollback transaction after rendering response instead of before

add middleware to detect students with disabled accounts

add 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 added datadog application to commom django apps and set it to use
a local statsd server by default.

* Fix open redirect vulnerability
* Add Logging To AUDIT_LOG : Note I had to change existing tests
  that mocked AUDIT_LOG with this
* Use external_auth.views.SHIBBOLETH_DOMAIN_PREFIX in student.views
* Add a bunch of documentation
* PEP8 / Pylint

* If a shib users type in their email on the regular login page,
  redirects them to /shib-login/
* Modify student.views.accounts_login to handle redirects
  generated by @login_required for courses that use shib for
  access control.
  Redirect those logins to /shib-login/?next=

Includes Data + Schema migrations for optout email -> user.id change.
Note that migrations should be reversible.

Switch to using decorators; refactor and cleanup tests.

Adds a new Email link to the instructor dashboard for frontend interface to send
email to course members. Adds a feature flag ENABLE_INSTRUCTOR_EMAIL to toggle this.
Creates a new djangoapp bulk_email that handles this action by getting the recipient
list and batching the emails to different celery tasks to do the actual sending.
Requires lynx package to convert HTML email to plaintext. Handles SMTP errors by
retrying or falling through to the next email. Adds the option to opt out of course
specific emails in the user dashboard with an Email Settings link for each course.
Uses severable configurable settings with defaults. DEFAULT_BULK_FROM_EMAIL
specifies the from address for email. EMAILS_PER_TASK specifies the number of emails
each celery task takes on. EMAIL_HOST, EMAIL_PORT, EMAIL_HOST_USER,
EMAIL_HOST_PASSWORD, and EMAIL_USE_TLS for the SMTP email backend settings.

Co-authored-by: Akshay Jagadeesh <akjags@gmail.com>

Also clarifies the contraction of location.course_id by throwing an exception for lcoations that are not of category course.

Add test for course_id method.

Features coming down the pipe will want to be able to:
* Refer to enrollments before they are actually activated (approval step).
* See what courses a user used to be enrolled in for when they re-enroll in
  the same course, or a different run of that course.
* Have different "modes" of enrolling in a course, representing things like
  honor certificate enrollment, auditing (no certs), etc.

This change adds an is_active flag and mode (with default being "honor").
The commit is only as large as it is because many parts of the codebase were
manipulating enrollments by adding and removing CourseEnrollment objects
directly. It was necessary to create classmethods on CourseEnrollment to
encapsulate this functionality and then port everything over to using them.

The migration to add columns has been tested on a prod replica, and seems to be
fine for running on a live system with single digit millions of rows of
enrollments.