Strip down sequence navigaiton and more stripping of the courseware nav

common/lib/xmodule/xmodule/css/sequence/display.scss

lms/static/sass/base/_variables.scss

lms/static/sass/course/base/_base.scss

lms/static/sass/course/base/_extends.scss

lms/static/sass/course/courseware/_courseware.scss

lms/static/sass/course/courseware/_sidebar.scss

lms/static/sass/course/discussion/_question-view.scss

lms/templates/staticbook.html