LMS: adds message styling to the separate instructor_2 Sass file

- Changed save OE message text
- Fix ICE legend positioning and content
- Add space to "offensive" checkbox
- Change tracker variable in undo to correct one

- Change wording when done with peer grading ("evals" -> "assessments")
- Added ICE legend item for comment syntax
- Added conditionals to display human readable 'grader_type' to alleviate confusion
- Rename 'Show/Hide Prompt' to 'Show/Hide Question'
- Reworded grading flags
- Make ICE grading container larger to more easily allow users to read and edit larger texts
- Adjusted lots of text and word choices to make them more user friendly
- Disable previous arrow on first grader feedback and next arrow on last grader feedback
- hide ORA instructions and ICE legend when calibrating so students don't feel like they need to write feedback

Changes after comments:

- Renamed instructions element and fixed casing issue
- Renamed legend class to ice-legend
- Changing condition from != to >= to not only fix incorrect one but also catch possible weirdness
- Grammar fix in a message
- Removing grader_type conditional in HTMl to give way to the one in python
- Moving ice feedback area height styling to CSS file

More changes:

- Update ICE version
- Modifying test to reflect code change
- Adding ICE undo feature

LMS/Accounts: Converts many class-based Sass archetype-focused @extends to use Sass placeholder syntax

Squashed commits to facilitate cherry-picking.  Committers and
original commit messages are:
- ==> @caesar2164, * ==> @jrbl, ~ ==> @jbau

- Added boolean to OE problem CMS settings to turn on ICE track changes
- Added ICE init and tracking start/stop to HTML
- Conditional in Peer Grading HTML for ICE container
- CSS styling for ICE container and insertion/deletion elements
- Added class to track changes HTML
- Added ice.min.js as well as included it in the js requirements for peer grading
- Use track_changes in peer_grading_problem
* Refactor peer_grading_problem to lookup track_changes variable by problem location.
* Whitelist ICE insert, delete tags
* Adds ICE multi-user-editor insert and delete tags to the peer grading sanitize_html whitelist.
- add reset button

* Introduction ICE means we need its inline tags to get passed through
  to the feedback target, but we don't want malicious peer feedback
  providers introducing <script>, etc, so we use lxml.html.clean to
  scrub peer grading input.
* Adds feedback URL autoheating.
* Allows ICE <insert> and <delete> tags but not others.

~ add helptext re: EXPERIMENTAL FEATURES

~ address a bunch of @VikParuchuri review comments on ICE for OEE
  ~ remove extraneous code
  ~ change to new xmodule accessors
  ~ refactor filtering

~ fix broken test test_peer_grading_problem

~ Create track_changes.coffee and remove <script> from
  peer_grading_problem.html
~ Remove all reliance on id in favor of local scoping and classes

~ bring up test coverage somewhat

~ remove superflous $.scrollTo

~ TODO: Filtering

* Uses override_settings to provide test variable
* Move location of cms link to upper right
* PEP8 / Pylink

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>

cleaned up padding for peer review training and grading states, removed extraneous response label,fixed style issue on rubric for peer grading where rubric items had a background color overridding the intended style

styling of peer review interface for students along with minimal adjustments to the staff grading interface as well. added internationalization of peer grading strings.

visual styling changes to staff grading and peer grading, along with additional instances of the use of the baseline variable instead of pixel definitions for padding and margins.

make year_of_birth graph bigger, add display names to analytics, remove extra context, fix typos & formatting

- rename list copy
- add beta list
- fix forum and admin API's to be more similar
- add auto-enroll checkbox
- fix list reload
- remove extra js logging
- add course errors visibility toggle
- add underscore.js check

Fixes subtitles hiding on slidermove and their height.