Also update studio-frontend to version 1.7.1

Adds a new React factory for that page to handle the logic. Also
cleans up the UI a little (centers it, stops using serif font, etc).

Open edit image modal via a custom signal

Send img tag attributes in open signal

Send natural image dimensions if no attr specified

Add new modal button in addition to old button

Also load built CSS when waffle switch on

Swap out TinyMCE toolbar button on waffle switch

Pass LANGUAGE_CODE from Django to template to studio-frontend

Define request.LANGUAGE_CODE in test_container_page.py

Learner-3925

Learner-3925

update eslint violations

Learner-3925
Learner-4388

Includes a hotfix for the page sock on the assets page.

remove erroneous asset_index listing

remove indirect define

remove pageFactoryArguments index

max length seems excessive for this file

lintfix

un-vendor backbone associations

add ConfigurationModelFixture for Studio Frontend Assets Page and add Bok Choy tests for Studio Frontend Assets Page

EDUCATOR-1613, edx-platform changes

update styles

html updates

add waffle flags

fix waffle flags

update css

updated css

make modal experimental

add waffle flag