Bok-choy fixtures, Studio tests, and (some) ORA tests

Refactored bok-choy directory structure
Added fixtures for course and xblock creation
Added bok-choy Studio tests
Added bok-choy tests for ora self- and ai- assessment
Refactored auto-auth; added staff and course-enrollment options
Removed extra javascript properties from page objects
Many Pylint and pep8 fixes

@jzoldak This includes the changes from https://github.com/edx/edx-platform/pull/2091

Suggested reviewers: @jzoldak @singingwolfboy