Escape xblock model field in string editor

Also add standalone spec

STUD-1984
Adds more comprehensive bokchoy testing for publishing changes
Merge pull request #4468 from edx/dan-f/support-quotes-in-string-field-editor

Support single and double quotes in xblock string field editor
Merge pull request #4499 from edx/benmcmorran/publishing-bokchoy

Adds more comprehensive bokchoy testing for publishing changes
Adds earlier changes from Dan and Andy
Fixes failing tests in test_studio_container.py
Fixes staff outline bug
Adds deletion tests
Adds name editing tests
Adds expand collapse tests
Adds default state tests
Adds promise for unit creation
Cleanup
Make names editable on creation on outline page
Fixes no content message when deleting all sections
Adds two misc tests