Add the text_customization dict in advanced settings, which contains
customizations checked in specific spots. Here it is used to enable
the customization of the "Check" and "Final Check" button titles
under the keys custom_check and custom_final_check.

Just works on the tabs list in mongo, nothing
deeper than that.
Added implementation functions in tabs.py,
providing a first step for some future
GUI editor.

Add the aria-haspopup attribute and additional explanatory text for
screen reader users.

Previously, if a course id contained a '-' character, links from that
page to threads would lead to 404s.

LTI blade allows to include LTI components to courses.
Python integration, Jasmine and acceptance tests are included.

LTI blade allows to include LTI components to courses.
Python integration, Jasmine and acceptance tests are included.

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>

Inspired by: http://eldarion.com/blog/2013/02/14/entry-point-hook-django-projects/
Moves startup code to lms.startup and cms.startup, and calls the startup
methods in wsgi.py and manage.py for both projects.

Rather than just calling `complex(...)` on the staff answers, also call
`calc.evaluator`. This way, simple things like `1/3` can be entered, as well
as more complicated explicit equations (e.g. `sqrt((12^2 + 26^2)/2)` etc, etc)

Simplify and update the tests to work with this.

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.

Also fixes a bug where message was not sent to user when entering 'denied'
state unless the user was previously in 'granted'.

Send notification to admin when a user enters 'pending' state.

Pylint cleanup.

STUD-554

Code review feedback.

Refactors trigger function.
Fixes Ui bugs: captions.
Fixes bug with Youtube on page load.
Hotfixes html5 video streaming bug.
Adds test video files to the project.

Add audit log definition, and use for logging of logins in external_auth and student apps.  Move test_login to student app. Improve conditional tests for Shibboleth login logic.  (Does not include reconfiguring log settings.)