Merge master

common/djangoapps/external_auth/views.py

common/djangoapps/student/views.py

common/lib/xmodule/xmodule/abtest_module.py

common/lib/xmodule/xmodule/modulestore/xml.py

common/lib/xmodule/xmodule/x_module.py

common/lib/xmodule/xmodule/xml_module.py

lms/djangoapps/courseware/access.py

lms/djangoapps/courseware/courses.py

...goapps/courseware/management/commands/metadata_to_json.py

lms/djangoapps/courseware/models.py

lms/djangoapps/courseware/module_render.py

lms/djangoapps/courseware/views.py

lms/djangoapps/simplewiki/views.py

lms/djangoapps/staticbook/views.py

lms/envs/common.py

lms/envs/dev.py

lms/envs/dev_int.py

lms/envs/test.py

lms/templates/course_navigation.html