Clean up after hotfix to fix xml loading for import

Fix for PR 1119.

A Jasmine test was falling. It went unnoticed. The PR was merged. This
is a fix for it.

caption display problem

We had a bug where mixins weren't being applied before `load_from_xml`
was called. This meant that not all of the fields were being loaded
correctly. To fix it, we used the mixoligist from the runtime to apply
the mixins earlier in the process. However, that caused the mixins to be
applied twice.

The included fixes to xblock resolved the multiply-applied mixins, and
the fixes to the parsing code make it simpler to understand, and add
some unit tests of the parsing to boot.

This command loads the courses with the XMLModuleStore, and then exports
the fields contents as json in a diff-friendly way. This can then be
used to validate against regressions in the xml parsing code.

fix the bug that the first caption and the second one will become current at the same time when displaying right captions

Stanford paid course registration

Use comments to skip tests instead of a tag

Include / Link to How To Contribute wiki page

PdfViewer: Added missing link to compatibility.js

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

edx.org/LMS: Use/Style Semantic Text in Login and Registration Banners

Wrap logic for selecting options in acceptance tests

Migrate courses from old mongo to split

Second batch of ORA UI fixes (with an ICE bonus!)

use to instantiate loc_mapper
test loc_mapper injection into split modulestore

Don't undo inheritance by unsetting course_entry structure
Do finer-grained cache clearing

Create location mapping
Create draft and published course with proper content in split.

- Change variable name to make it more clear

- 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

Add asset locking to the Studio asset page.

Replace date lib w/ simpler tzAbbr

Dev Environment: Disabling Sass Debug Mode

Add "Download CSV of all student anonymized IDs" button to instructor dashboards