Make it more active.  Adds a separate section for edX.org-specific copy,
because it's hard to make it generic.

LMS-11084

The email texts in lms/templates/emails are not extracted by rake i18n:generate because the babel_mako.cfg does not include them.
And a several emails are not translatable because they do not use ugettext.

LMS-1287

into beta dashboard.

Also includes new functionality, in both legacy and beta
dashboard, to include appropriate email text for a
Shibboleth course.

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

fix templates

    Added some text to guide the student to register with a particular email address.
    This is the one that was entered into the enrollment/invitation form by the instructor.
    Modified the template and associated test.

 Delay for possible race condition with fetching course email object.
 Use settings.SITE_NAME for host name to generate email footer url.

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>

Optionally email students on enroll/un-enroll actions
by instructor from enrollment tab in LMS.

Adjust language of LMS emails to work specifically for Stanford. Here
there be dragons: lots of ugly conditionals that will need to be
changed once we develop a way to "theme" arbitrary strings throughout
the site.

Instead of hardcoding things like the platform name, use the
corresponding overrideable settings instead. This allows themes to
control emails as well.

 - issue is that content machine isn't whitelisted for email
 - this also provides secondary filtering for user registration

  - django debug commented out in lms/envs/dev.py (temporarily - need cleanup)
  - email backend set
  - index page modified for edx4edx