Refactor staff preview menu logic out of template

.jshintignore

.jshintrc

lms/static/karma_lms.conf.js

lms/static/karma_lms_coffee.conf.js

lms/static/lms/fixtures/preview/course_preview.html

lms/static/lms/js/build.js

lms/static/lms/js/preview/preview_factory.js

lms/static/lms/js/spec/main.js

lms/static/lms/js/spec/main_requirejs_coffee.js

lms/static/lms/js/spec/preview/preview_factory_spec.js

lms/templates/courseware/course_navigation.html