Merge remote-tracking branch 'origin/master' into feature/alex/poll-merged

Conflicts:
	common/lib/xmodule/xmodule/capa_module.py
	common/lib/xmodule/xmodule/foldit_module.py
	common/lib/xmodule/xmodule/tests/__init__.py
	common/lib/xmodule/xmodule/tests/test_capa_module.py
	common/lib/xmodule/xmodule/tests/test_combined_open_ended.py
	common/lib/xmodule/xmodule/tests/test_conditional.py
	common/lib/xmodule/xmodule/tests/test_self_assessment.py