Fixes tests, adds internationalized strings for new state tooltips, corrected tooltip javascript, etc.

Iniital refactor of capa styling for basic checkbox and multiple choice problem types, including additional comments to sass styles

Use native checkboxes for courseware license options
In Studio settings editor for video module, don't show license if feature-flagged off
Don't let Scope.contents fields leak to Studio editor
JS gettext() must all be on the same line for i18n
Add docstrings for bok-choy tests
Remove LicenseMixin from HTMLDescriptor
Responding to UX review feedback
Add aria-pressed attribute
Use https links instead of protocol-relative links for links to creativecommons.org
Remove license from course outline page in Studio

* updating vendor files
* updating class syntax (to new FA-based classes) for all UI elements
* correcting broken tests

SASS compilation variable conventions update, focusing on basic colors, baseline variable usage for padding and margins, ui-depth extends, along with other small fixes. The intent with this is to not have any user-facing impact, and instead move us closer toward having files that use our newer sass conventions.

* removing unused font-family-centric Sass variables
* removing unused graphic images and Sass references
* clean up of style removal fallout

* moving font-size to use @include font-size() mixin
* re-organizing vendor reset styling into _vendor.scss override rather than _reset.scss
* initial rule re-organization and minor line-height tweaks

cleanup of unit, container, and xblock sass; added modules and layout sass; publishing states and actions on new unit

STUD-1312

Studio: revising .fake-link utility class to use Sass placeholder and syncing commenting style

LMS: updating Sass ui-disabled placholder syntax and creating utility is-disabled class

Studio: adding in basic action Sass placeholder for use in enabling/disabling UI

Studio: applying action Sass placeholder to publish/create-draft Unit view actions

STUD-1497

STUD-1306

styling for recursive xblock rendering structure to be used in the container page, pulling from general xblock styles in a separate file.

Also includes RequireJS changes.

Fixes bugs:
STUD-755, STUD-152, STUD-700, STUD-699