Pick up last few weeks of edX changes up to (and including) last week's
hotfix.
Conflicts:
common/djangoapps/student/models.py
common/djangoapps/student/views.py
common/lib/xmodule/xmodule/capa_base.py
common/lib/xmodule/xmodule/tabs.py
docs/en_us/developers/source/xblocks.rst
lms/djangoapps/certificates/views.py
lms/djangoapps/courseware/views.py
lms/envs/common.py
lms/templates/courseware/course_about.html
lms/templates/courseware/course_navigation.html
lms/templates/instructor/instructor_dashboard_2/metrics.html
lms/templates/problem.html
lms/templates/register.html
requirements/edx/github.txt
